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Secondary 1 · Mathematics
Algebra · Algebra

Monomials and Operations with Monomials

In a video game you collect energy gems that are worth $x$ points each. On the first screen you get $5x$, on the second $8x$, and on the third you lose $3x$ because of a spell. How many points do you have in total? To find out, you need to operate with monomials.

What a monomial is

Diagram of the monomial −5x²y showing its coefficient −5, its literal part x²y, and its degree 3, obtained by adding the exponents 2 and 1. −5 x²y coefficient literal part degree = 2 + 1 = 3 (the y has exponent 1, even though it is not written)

Not everything with letters is a monomial: $\frac{4}{x}$ is not (the letter is in the denominator) and neither is $\sqrt{x}$ (the exponent is not a natural number). $2 + a$ is not either: it has two terms separated by a $+$, so it is a binomial, not a monomial.

Two monomials are like monomials if they have exactly the same literal part: $4x^2$ and $2x^2$ are; $4x^2$ and $4x$ are not, even though they look similar.

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In the world of algebra, not all expressions are "monomials". Remember that a monomial is a product of a number and one (or more) letters with natural number exponents.…

In the world of algebra, not all expressions are "monomials". Remember that a monomial is a product of a number and one (or more) letters with natural number exponents. State which of the following expressions are monomials and which are not. If not, explain why:

  1. a) $5x^3$
  2. b) $2 + a$
  3. c) $-3ab^2$
  4. d) $\frac{4}{x}$
  5. e) $x$
  6. f) $\sqrt{x}$
Solve
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Copy the following table into your notebook and complete the missing elements for each monomial. Be careful with signs and invisible exponents! | Monomial | Coefficient…

Copy the following table into your notebook and complete the missing elements for each monomial. Be careful with signs and invisible exponents!

Monomial Coefficient Algebraic Part Degree
$-7x^4$
$abc$
$\frac{1}{2}x^2y$
$-x$
$12$ None
Solve
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Two monomials are "like terms" if they have exactly the same algebraic part. In the list below, there are three hidden pairs of like monomials. Find and group them!…

Two monomials are "like terms" if they have exactly the same algebraic part. In the list below, there are three hidden pairs of like monomials. Find and group them!

  • $4x^2$

  • $-5ab$

  • $\frac{1}{3}x$

  • $2x^2$

  • $8ab$

  • $-7x$

Solve
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In a strategy video game, resources are stored using algebraic expressions. Complete the following table so the programmer can organise the inventory correctly: |…

In a strategy video game, resources are stored using algebraic expressions. Complete the following table so the programmer can organise the inventory correctly:

Monomial Coefficient Algebraic Part Degree
$-5x^2y$
$a^3b$
$\frac{2}{3}z^4$
$-m$
Solve

Adding and subtracting monomials

Two squares of x² and a rectangle of x cannot be combined into a single monomial because they are not like terms. x² x² + x = 2x² + x cannot be combined into a single monomial: x² and x are not like terms
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Simplify these expressions by adding or subtracting like monomials. If an expression cannot be simplified, explain why: a) $3x + 5x - 2x$ b) $7a^2 - a^2$ c) $4x + 3y$ d)…

Simplify these expressions by adding or subtracting like monomials. If an expression cannot be simplified, explain why:

  1. a) $3x + 5x - 2x$
  2. b) $7a^2 - a^2$
  3. c) $4x + 3y$
  4. d) $5ab + ab - 3ab$
  5. e) $x^3 + x^3 + x^3$
Solve
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In an adventure video game, your character collects energy gems. Red gems are worth $x$ points each. If during the first level you get $5x$ gems, in the second level you…

In an adventure video game, your character collects energy gems. Red gems are worth $x$ points each. If during the first level you get $5x$ gems, in the second level you find another $8x$, and in the third level you lose $3x$ due to a spell, simplify the expression to find out how many gems you have in total at the end.

Solve
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You are organising the files on your computer. To save space, you can only add or subtract "files" (monomials) that are like terms. Simplify the following expression as…

You are organising the files on your computer. To save space, you can only add or subtract "files" (monomials) that are like terms. Simplify the following expression as much as possible:

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

Solve
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We want to surround a shelf with a special polygonal shape with an LED strip. Calculate the monomial that represents the total perimeter of the figure by adding its…

We want to surround a shelf with a special polygonal shape with an LED strip. Calculate the monomial that represents the total perimeter of the figure by adding its sides:

x 4x 2x 2x 2x 2x 4x
Solve

Multiplying monomials

Rectangle with base 6y and height 4 whose area illustrates the product of monomials: 4 times 6y is 24y. 6y (base) 4 (height) Area = 4 · 6y = 24y

Power of a monomial

Raising a monomial to a power means multiplying it by itself several times. That is why you raise the coefficient and each letter to the power, and for the letters you multiply the exponents.

$$(2x^3)^2 = 2x^3 \cdot 2x^3 = 4x^6$$
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Perform the following multiplications of monomials, remembering to multiply the coefficients together and add the exponents of identical letters: a) $3 \times (4x)$ b)…

Perform the following multiplications of monomials, remembering to multiply the coefficients together and add the exponents of identical letters:

  • a) $3 \times (4x)$

  • b) $2x \times 5x$

  • c) $(-3a^2) \times 2a$

  • d) $4x \times 3y$

Solve
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To organize a party, you buy multipacks of soft drinks. Each pack contains $6$ cans and the price of one can is $y$ pesos. If you buy $4$ identical packs, write the…

To organize a party, you buy multipacks of soft drinks. Each pack contains $6$ cans and the price of one can is $y$ pesos. If you buy $4$ identical packs, write the monomial that represents the total cost of the purchase.

Hint: First find out how many cans there are in total and then multiply by the price of one.

Solve
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A farmer has a rectangular vegetable patch to plant tomatoes. Help him calculate the expression for the area of the vegetable patch by multiplying the following…

A farmer has a rectangular vegetable patch to plant tomatoes. Help him calculate the expression for the area of the vegetable patch by multiplying the following monomials:

5a 3b Area = ? Area = Base · Height
Solve
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In the comic book store, $x$ represents an amount of manga. If Luis buys three times the square of that amount and then gets a discount of twice the square of that…

In the comic book store, $x$ represents an amount of manga. If Luis buys three times the square of that amount and then gets a discount of twice the square of that amount, what monomial represents the final amount of manga he paid for? Write down the operation and simplify.

Solve

Dividing monomials

The divisor must be different from zero. In the examples in this section, assume that the letters in the divisor are worth something other than $0$. If subtracting the exponents gives a negative exponent, the result is not a monomial.

Division of monomials: 24x⁶ divided by 4x² gives 6x⁴; the coefficients are divided and the exponents are subtracted. coefficients: 24 ÷ 4 = 6 · exponents: 6 − 2 = 4 24x⁶ 4x² = 6x⁴

Finding the missing monomial

To find an unknown monomial you use the inverse operation, just as with numbers.

  • If an addend is missing: subtract the other addend from the total.

  • If a factor is missing: divide the product by the known factor.

  • If the divisor is missing: divide the dividend by the quotient.

  • If the dividend is missing: multiply the quotient by the divisor.

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Simplify the following divisions of monomials: a) $\frac{15x^6}{3x^2} =$ b) $\frac{-20a^4}{5a^3} =$ c) $\frac{8y^3}{8y^3} =$

Simplify the following divisions of monomials:

  1. a) $\frac{15x^6}{3x^2} =$
  1. b) $\frac{-20a^4}{5a^3} =$
  1. c) $\frac{8y^3}{8y^3} =$
Solve
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A streaming server divides a data packet of size $24x^6$ among $4x^2$ users. Write the monomial that represents the amount of data each user receives.

A streaming server divides a data packet of size $24x^6$ among $4x^2$ users. Write the monomial that represents the amount of data each user receives.

Solve
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A "Mystery Monomial" has lost some of its parts after passing through an operation machine. Your mission is to reconstruct the original equation by finding the missing…

A "Mystery Monomial" has lost some of its parts after passing through an operation machine. Your mission is to reconstruct the original equation by finding the missing monomial in each case (represented by the symbol $?$):

  1. a) $? + 7a^2b - 3a^2b = 10a^2b$
  1. b) $(? \times 5x^4) : 2x^2 = 15x^5$
  1. c) $\frac{24y^{10}}{?} = 4y^5$
Solve

Areas with monomials

The measurements of a figure can be monomials. Remember the area formulas:

A triangle takes up half of a rectangle with the same base b and the same height h. base b h triangle = b · h ÷ 2
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A street artist is designing a mural with intertwined geometric shapes. The central design consists of a large rectangle with base $5x^2$ and height $3y$. Inside this…

A street artist is designing a mural with intertwined geometric shapes. The central design consists of a large rectangle with base $5x^2$ and height $3y$. Inside this rectangle, the artist leaves an unpainted gap in the shape of a triangle whose base measures $2x^2$ and whose height is $y$. Write the simplified monomial representing the area that will finally be painted in color.

Painted area Gap 5x² 3y 2x² y
Solve
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Look at the design of this play area for a technology park. The municipality needs to calculate the total area to install artificial turf of different colors in each…

Look at the design of this play area for a technology park. The municipality needs to calculate the total area to install artificial turf of different colors in each section.

2x 3x 4x Zone A Zone B₁ Zone B₂

Calculate the following expressions using operations with monomials:

  1. The area of Zone A.

  2. The area of Zone B (formed by two identical triangles).

  3. The total area of the compound simplifying the sum of the resulting monomials.

Solve

Putting it all together: combined expressions

Real problems mix parentheses, sums, and products of monomials. The usual order still applies: parentheses and powers first, multiplications and divisions next, additions and subtractions last.

Rectangle with base b and height h that models the area when the base and the height are monomials. b · h base b h area of the rectangle base and height can be monomials: 3x² and 2x
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Apply the distributive property to expand the brackets and collect like terms in the following expression: $3 \times (2x + 4) + 5 \times (x - 2)$

Apply the distributive property to expand the brackets and collect like terms in the following expression:

$3 \times (2x + 4) + 5 \times (x - 2)$

Solve
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Find the expression for the area of the following rectangle as a monomial. Remember that area is calculated by multiplying the base by the height ($A = b \times h$).

Find the expression for the area of the following rectangle as a monomial. Remember that area is calculated by multiplying the base by the height ($A = b \times h$).

Area 5x 3x
Solve
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Simplify the following combined expression, paying close attention to the order of operations and the laws of indices: $$\frac{20x^6}{5x^2} + (3x^2 \times 4x^2) -…

Simplify the following combined expression, paying close attention to the order of operations and the laws of indices:

$$\frac{20x^6}{5x^2} + (3x^2 \times 4x^2) - \frac{(2x^3)^2}{x^2}$$

Explain step by step how you simplified each term before performing the final addition and subtraction. What is the degree of the resulting polynomial before total simplification?

Solve

Back to the beginning: you add and subtract the like monomials from the three screens: $5x + 8x - 3x = (5 + 8 - 3)x = 10x$. You have $10x$ points in total.

Summary

See all the exercises in this section