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Secondary 2 · Mathematics
Algebra · Algebra

Operations with Monomials

Before you start, make sure you know: Properties of exponents (Secondary Year 1 (first cycle))
Before you start, make sure you know: Monomials and operations with monomials (Secondary Year 1 (first cycle))

In a racing video game, each gold coin is worth $5x$ points and each silver coin is worth $2x$ points. If Wilkin collects 4 gold coins and 6 silver coins, how many points does he get in total? To find out, you need to be able to multiply and add monomials with ease.

Parts of a monomial and like monomials

A monomial has three parts you should be able to recognize: the coefficient (the number), the variable part (the letters with their exponents), and the degree (the sum of the exponents of the letters).

Monomial Coefficient Variable part Degree
$7x^3$ $7$ $x^3$ 3
$-a^2b$ $-1$ $a^2b$ 3
$-5$ $-5$ (none) 0

Two monomials are like monomials if they have exactly the same variable part. For example, $5x^2$ and $-x^2$ are like monomials, but $5x^2$ and $5x$ are not.

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To understand how mathematical expressions are constructed, it is essential to know the parts of a monomial. Complete the requested information for each of the following…

To understand how mathematical expressions are constructed, it is essential to know the parts of a monomial. Complete the requested information for each of the following monomials:

  1. a) $7x^{3}$
  2. b) $-a^{2}b$
  3. c) $\frac{1}{2}x^{4}y^{2}$
  4. d) $-5$

For each one, state:

  • The coefficient.

  • The literal part.

  • The degree of the monomial.

Solve
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In algebra, we can only add or subtract "like terms". Identify which of the following monomials are like terms and group them: $5x^{2}$, $-3x$, $\frac{1}{4}x^{2}$, $7y$,…

In algebra, we can only add or subtract "like terms". Identify which of the following monomials are like terms and group them:

$5x^{2}$, $-3x$, $\frac{1}{4}x^{2}$, $7y$, $x$, $-x^{2}$, $12x$, $2y$

Solve

Adding and subtracting like monomials

We can only add or subtract like monomials: you operate on the coefficients and the variable part stays the same.

$$3ab - 5ab + ab = (3 - 5 + 1)ab = -ab$$

Why? It is like counting identical objects: 3 bags minus 5 bags plus 1 bag is $-1$ bag.

Diagram of adding like monomials 3ab − 5ab + ab by operating on the coefficients 3 − 5 + 1 to get −ab. 3ab − 5ab + ab sum of coefficients = −ab (3 − 5 + 1 = −1)
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Simplify the following expressions by adding and subtracting like monomials: a) $5a + 3a - 2a$ b) $4x^{2} - x^{2} + 7x^{2}$ c) $3ab - 5ab + ab$ d) $x + x + x + x$

Simplify the following expressions by adding and subtracting like monomials:

  1. a) $5a + 3a - 2a$
  2. b) $4x^{2} - x^{2} + 7x^{2}$
  3. c) $3ab - 5ab + ab$
  4. d) $x + x + x + x$
Solve
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Fully simplify the following algebraic expression by grouping like monomials: $9x^3 - 5x^2 + 4x - 2x^3 + 7x^2 - x + 10$

Fully simplify the following algebraic expression by grouping like monomials:

$9x^3 - 5x^2 + 4x - 2x^3 + 7x^2 - x + 10$

Solve

Multiplying monomials

$$(3x^2) \cdot (5x^4) = (3 \times 5)(x^2 \cdot x^4) = 15x^6$$ Rectangle with base 5x and height 3x whose area is 15x² when both monomials are multiplied. 5x (base) 3x (height) Area = 3x · 5x = 15x²
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Calculate the product of the following monomials. Remember to multiply the coefficients together and add the exponents of identical letters: a)…

Calculate the product of the following monomials. Remember to multiply the coefficients together and add the exponents of identical letters:

  1. a) $(3x^{2}) \times (5x^{4})$
  2. b) $(-2a^{3}) \times (4a)$
  3. c) $(\frac{1}{2}x) \times (6x^{2})$
  4. d) $(-x^{2}) \times (-x^{3})$
Solve
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Calculate the result of the following monomial multiplications and simplify the literal part using index laws: a) $(4a^2b) \times (-3ab^3)$ b)…

Calculate the result of the following monomial multiplications and simplify the literal part using index laws:

  1. a) $(4a^2b) \times (-3ab^3)$
  1. b) $(\frac{1}{2}x^4) \times (6x^2)$
  1. c) $(-2z^3) \times (-5z^2) \times z$
Solve

Dividing monomials

$$\frac{15x^3y^2}{3x^2y} = \frac{15}{3}\,x^{3-2}y^{2-1} = 5xy$$
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Perform the following divisions of monomials. Remember to divide the coefficients and subtract the exponents of the letters: a) $(12x^{5}) : (3x^{2})$ b)…

Perform the following divisions of monomials. Remember to divide the coefficients and subtract the exponents of the letters:

  1. a) $(12x^{5}) : (3x^{2})$
  2. b) $(-10a^{4}) : (5a^{3})$
  3. c) $(15x^{3}y^{2}) : (3x^{2}y)$
  4. d) $(4x^{2}) : (2x^{2})$
Solve
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Simplify the following monomial quotients. Express the result as a single monomial where possible: a) $\frac{20x^6}{5x^2}$ b) $(-12a^3b^2) : (3a^2b^2)$ c)…

Simplify the following monomial quotients. Express the result as a single monomial where possible:

  1. a) $\frac{20x^6}{5x^2}$
  1. b) $(-12a^3b^2) : (3a^2b^2)$
  1. c) $\frac{15m^4n^2}{10m^2}$
Solve

Power of a monomial

$$(2x^3)^2 = 2^2 \cdot (x^3)^2 = 4x^6$$
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Calculate the power of these monomials. Do not forget to raise both the coefficient and the literal part to the indicated exponent: a) $(2x^{3})^{2}$ b) $(-3a^{2})^{2}$…

Calculate the power of these monomials. Do not forget to raise both the coefficient and the literal part to the indicated exponent:

  1. a) $(2x^{3})^{2}$
  2. b) $(-3a^{2})^{2}$
  3. c) $(x^{4})^{3}$
  4. d) $(-2x)^{3}$
Solve
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Work out the following powers of monomials. Remember that the exponent affects both the coefficient and each of the variables in the literal part: a) $(-3x^4)^2$ b)…

Work out the following powers of monomials. Remember that the exponent affects both the coefficient and each of the variables in the literal part:

  1. a) $(-3x^4)^2$
  1. b) $(2a^2b^3)^4$
  1. c) $(-\frac{1}{2}m^5)^3$
Solve

Combined operations

The usual order of operations applies: first parentheses and exponents, then multiplication and division, and finally addition and subtraction (only between like terms).

Distributive property

When a monomial multiplies a sum, you multiply it by each term:

$$-3ab^2 \cdot (2a^2 - 5ab) = -6a^3b^2 + 15a^2b^3$$

Afterward, combine like terms, if there are any.

Unknown monomials

To find $M$ in $(-4x^3y^2) \cdot M = 20x^7y^5$, use the inverse operation: $M = \dfrac{20x^7y^5}{-4x^3y^2} = -5x^4y^3$.

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Solve the following combined operations with monomials, respecting the order of operations: a) $5x^2 \times 2x + 12x^4 : 3x$ b) $3ab \times (2a^2b) - (5a^3b^2)$ c)…

Solve the following combined operations with monomials, respecting the order of operations:

  1. a) $5x^2 \times 2x + 12x^4 : 3x$
  1. b) $3ab \times (2a^2b) - (5a^3b^2)$
  1. c) $(2n^3)^2 - 5n^6 + n^2 \times n^4$
Solve
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Work out the following combined operation with monomials, fully simplifying the result. Pay special attention to the order of operations and power rules: $$…

Work out the following combined operation with monomials, fully simplifying the result. Pay special attention to the order of operations and power rules:

$$ \frac{2}{3}x^2 \times (-3x^3)^2 - 5x^5 \times (2x^3) + \frac{16x^{10}}{2x^2} $$
Solve
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Find the unknown monomials $M$ and $N$ that make the following equalities true: a) $ (-4x^3y^2) \times M = 20x^7y^5 $ b) $ \frac{N}{-3ab} = 6a^2b^3 $ c)…

Find the unknown monomials $M$ and $N$ that make the following equalities true:

  1. a) $ (-4x^3y^2) \times M = 20x^7y^5 $
  1. b) $ \frac{N}{-3ab} = 6a^2b^3 $
  1. c) $ (2x^2)^3 : M = -4x $
Solve
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Calculate the value of the resulting monomial at the top of this "product pyramid", where each brick is the product of multiplying the two monomials directly below it:

Calculate the value of the resulting monomial at the top of this "product pyramid", where each brick is the product of multiplying the two monomials directly below it:

× × × −2x 3x² -x³ A B ¿?
Solve
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Simplify the following expression by applying the distributive property and combining the resulting like monomials: $$ -3ab^2 \times (2a^2 - 5ab + b^2) - 2a^2b \times…

Simplify the following expression by applying the distributive property and combining the resulting like monomials:

$$ -3ab^2 \times (2a^2 - 5ab + b^2) - 2a^2b \times (4ab - a) $$
Solve

Common factor of monomials

Factoring out a common factor is the reverse process of the distributive property. You take out the GCF of the coefficients and each common letter with its smallest exponent.

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Factorise out the highest common factor in the following algebraic expression. Remember to extract both the highest common factor of the coefficients and the common…

Factorise out the highest common factor in the following algebraic expression. Remember to extract both the highest common factor of the coefficients and the common variables with their lowest exponent:

$$ 24x^5y^4z^2 - 36x^3y^6z^3 + 12x^2y^4z^5 $$
Solve

Areas, perimeters, and volumes with monomials

The area of a rectangle is base times height: you multiply the monomials. The perimeter is the sum of the sides: you combine like terms. The volume of a cube with edge $a$ is $a^3$.

Rectangle with base 3x and height x illustrating how to find its area by multiplying and its perimeter by adding. 3x x Area = 3x² Perimeter = 8x
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Find the algebraic expression representing the perimeter of the following rectangular plot for a school garden. Once you have the expression, fully simplify it by…

Find the algebraic expression representing the perimeter of the following rectangular plot for a school garden. Once you have the expression, fully simplify it by combining like terms.

3x x
Solve
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Find the simplified algebraic expression representing the perimeter of the following plot designated for a play area in a park:

Find the simplified algebraic expression representing the perimeter of the following plot designated for a play area in a park:

5x x 2x 2x 2x 2x
Solve
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Find the expression representing the area of the shaded region in the following figure, knowing that the side of the outer square measures $4x$ and the side of the inner…

Find the expression representing the area of the shaded region in the following figure, knowing that the side of the outer square measures $4x$ and the side of the inner white square measures $x$:

4x x
Solve
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A design company manufactures aluminum frames for tablet screens. The design follows the proportions shown in the following figure, where all measurements are expressed…

A design company manufactures aluminum frames for tablet screens. The design follows the proportions shown in the following figure, where all measurements are expressed in terms of a variable $x$. Find the monomial representing the total surface area of the frame (the shaded region).

Area = ? 6x 4x 4x 2x
Solve
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Calculate the monomial representing the volume of a 3D shape formed by joining 5 identical cubes, where the edge of each cube measures $ \frac{2}{3}x^2 $ meters. Express…

Calculate the monomial representing the volume of a 3D shape formed by joining 5 identical cubes, where the edge of each cube measures $ \frac{2}{3}x^2 $ meters. Express the final result in simplified form.

2 3 x² × 5
Solve

Problems with monomials

Many problems can be translated into monomials: you write each quantity as a monomial and multiply or add depending on the situation.

In the video game problem (energy = attack × defense ÷ fatigue), you multiply and then divide: $\dfrac{12a^2b^3 \cdot 5a^3b}{10ab^2} = \dfrac{60a^5b^4}{10ab^2} = 6a^4b^2$, which has degree $6$.

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In a racing video game, for each gold coin collected you get $5x$ points and for each silver coin you get $2x$ points. If in a game a player has collected 4 gold coins…

In a racing video game, for each gold coin collected you get $5x$ points and for each silver coin you get $2x$ points.

If in a game a player has collected 4 gold coins and 6 silver coins:

  1. a) Write the monomial representing the total points from the gold coins.
  2. b) Write the monomial representing the total points from the silver coins.
  3. c) Add both monomials to find the total points for the game.

You can do it on paper and send a photo with your answer.

Solve
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In a tree-planting campaign, each volunteer plants $3x$ trees in the morning and $2x$ trees in the afternoon. If there are a total of $y$ volunteers, write the…

In a tree-planting campaign, each volunteer plants $3x$ trees in the morning and $2x$ trees in the afternoon. If there are a total of $y$ volunteers, write the simplified algebraic expression representing:

  1. a) The total number of trees planted by a single volunteer in one day.
  1. b) The total number of trees planted by all volunteers in a week (7 days).
Solve
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In a strategy video game, a battalion's energy is calculated by multiplying its attack level by its defence level, divided by its fatigue. Given that: Attack:…

In a strategy video game, a battalion's energy is calculated by multiplying its attack level by its defence level, divided by its fatigue. Given that:

  • Attack: $ 12a^2b^3 $

  • Defence: $ 5a^3b $

  • Fatigue: $ 10ab^2 $

Express the total energy of the battalion as a single monomial and determine its degree.

Solve

Back to the beginning: the 4 gold coins are worth $4 \cdot 5x = 20x$ points and the 6 silver coins are worth $6 \cdot 2x = 12x$. They are like monomials, so we add them: Wilkin gets $20x + 12x = 32x$ points.

Summary

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