I. Model Problems. II. Practice III. Challenge Problems VI. Answer Key

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I. Model Problems. II. Practice III. Challenge Problems VI. Answer Key

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I. Model Problems A monomial is an expression that is a number, variable or product of a number and variables. Examples of monomials: –3, 4x, 5xy, y2 To multiply monomials, multiply all the coefficients and all the variables. Example 1 Simplify 2x3(7x5). = 14x3x5

Multiply the coefficients.

= 14x8

Multiply variables.

The answer is 14x8. To divide monomials, divide the coefficients and the variables. 20x 7 y 6 Example 2 Simplify . 4x 2 y 5 Divide the coefficients. 5x 7 y 6 = 3 5 x y = 5x4y Divide variables. The answer is 5x4y. When you have power of a power, everything inside the parentheses gets raised to the power. You multiply exponents. Example 3 Simplify (5x2y4)3. = 53x2•3y4•3

Raise everything to the 3rd power.

= 125x6y12

Simplify.

The answer is 125x6y12.

To multiply rational expressions with monomials, in the numerator and the denominator, follow the rules of simplifying monomials. 15x 7 y 6 xy 6 Example 4 Multiply .  2x 2 y 5 5y 3 Multiply the numerators and the 15x 7 y 6  xy 6 = 2 5 denominators. 2x y 5y 3

15x 7 y 6  xy 6 = 10x 2 y 5  y 3

Multiply the coefficients.

15x 8 y12 = 10x 2 y 8

Multiply the variables (add exponents).

3x 8 y12 = 2x 2 y 8 3 = x6 y4 2

Simplify coefficients. Divide variables (subtract exponents).

3 6 4 x y . 2 (3x 2 y 3 )3 4x 2 y 5  Example 5 Multiply . 2x 2 y 5 18y 3 Simplify power to a power. 27x 6 y 9 4x 2 y 5  = 2x 2 y 5 18y 3 Multiply the coefficients and 108x 8 y14 = variables. 36x 2 y 8

The answer is

3x 8 y14 = 2 8 x y = 3x 6 y 6 The answer is 3x6y6.

Simplify coefficients. Divide variables (subtract exponents).

II. Practice Simplify. 1. 4x5(9x3)

2. –9x5(7x7)

3. –7x5(3x2)

4. 20x4(3x9)

5. 8x7y5(10x2y)

6. –4x9 y15(3x9y5)

20x14 7. 10x 3

30x13 8. 15x 8

120x10 9. 10x 5

45y16 10. 9 y8

65x19 y17 11. 13x 5 y 5

30x 27 y 39 12. 5x10 y 8

13. (4x2y5)3

14. (2x3y2)5

15. (–2x3y7)3

16. (7x2yz4)2

17. (10x24y20)2

18. (–3x5y10)3

3x 6 y11 20x 5 y 8  19. 10x 2 y 5 12x 4 y 3

24x12 y 23 15x 3 y 3  20. 4x 7 y 20 25x 2 y 2

24x19 y 20 15x12 y19  21. 12x17 y14 3x 9 y15

14x 8 y 6 (2x 3 y 3 )2  22. 7x 3 y 3 2x 2 y

III. Challenge Problems 23. What is the area of a rectangle with length 6xy7 inches and width (5x2y) inches? Write your answer as an expression in terms of x and y.

20x19 y 20 4x54 y19 z 20 (4x12 y19 z)3 24. Simplify .   8x17 y14 (2x 9 y15 )3 3x 4 y15 z 2

25. Correct the Error There is an error in the student work shown below: Question: (3x4y9)5 . Solution:

= (3x4y9)5 = 15x20y45

What is the error? Explain how to solve the problem. _________________________________________________________ _________________________________________________________

IV. Answer Key 1. 36x8 2. -63x12 3. -21x7 4. 60x13 5. 80x9y6 6. -12x18y20 7. 2x11 8. 2x5 9. 12x5 10. 5y8 11. 5x14y12 12. -6x17y31 13. 64x6y15 14. 32x15y10 15. -8x9y21 16. 49x4y2z8 17. 100x48y40 18. -27x15y30 19. (1/2)x6y11 20. (18/5)x6y4 21. 10x5y10 22. 4x9y8 23. 30x2y8 in2 24. (80/3)x61y22z21 25. The student multiplied the coefficient by the exponent instead of raising the coefficient to the power. The correct answer is 243x20y45.