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ESO Y2 · Mathematics
Algebra · Algebra

Operations with monomials

In a racing video game, each gold coin is worth $5x$ points and each silver coin is worth $2x$ points. If you collect 4 gold coins and 6 silver coins, how many points do you score? To find out, you need to multiply and add monomials fluently.

Before you start, make sure you know: Properties of powers (1st ESO)
Before you start, make sure you know: Monomials and operations with monomials (1st ESO)

Multiplying monomials

$$(3x^2) \cdot (5x^4) = (3 \cdot 5)\,(x^2 \cdot x^4) = 15x^6$$ Rectangle with base 5x and height 3x whose area is 15x² when the two 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) $(3x^{2}) \cdot (5x^{4})$…

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

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

Dividing monomials

$$\frac{15x^3y^2}{3x^2y} = \frac{15}{3}\,x^{3-2}y^{2-1} = 5xy$$ Algebraic fraction representing the division of 12x⁵ by 3x² to obtain 4x³. 12x⁵ gems shared out 12x⁵ 3x² = 4x³ per player
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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

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

Like monomials: adding before operating

Before multiplying or dividing, remind yourself which monomials can be added: only like monomials, by operating on their coefficients.

$$3ab - 5ab + ab = (3 - 5 + 1)ab = -1ab = -ab$$ Diagram of adding like monomials 3ab − 5ab + ab by operating on the coefficients 3 − 5 + 1 to give −ab. 3ab − 5ab + ab sum of coefficients = −ab (3 − 5 + 1 = −1)
Practice★☆☆Not started
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

Putting it all together: areas with monomials

The area of a rectangle is base times height. If both are monomials, the area is calculated by multiplying them, and the perimeter by adding the four sides.

Rectangle with base 3x and height x illustrating the calculation of its area by multiplying and its perimeter by adding. 3x x Area = 3x² Perimeter = 3x+x+3x+x = 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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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

Back to the beginning: The 4 gold coins are worth $4 \cdot 5x = 20x$ points and the 6 silver coins are worth $6 \cdot 2x = 12x$ points. Since they are like monomials, they can be added: you score a total of $20x + 12x = 32x$ points.

Summary

See all the exercises in this section