G8

Math Task

Unit 2 · Lesson 12: Solve Square & Cubic Equations

(^)
Directions: Solve.

Circle the equation in which 푥푥 has the
greater value.
푥푥^3 = 160− 35
푥푥^2 = 25−(−11)

Solution:

푥푥^3 = 160− 35
푥푥^3 = 125
�^3 푥푥^3 =√^3125
√^3 푥푥∙푥푥∙푥푥=√^5 ∙^5 ∙^5

(^3)
푥푥= 5

• 푥푥^2 = 25−(−11)

푥푥^2 = 36

�푥푥^2 =√ 36

√푥푥∙푥푥=√^6 ∙^6

푥푥= ±6

In the second equation, 푥푥 has a greater value when
the it equals positive 6.

The value of 푥푥 in first equation is greater only
when the value of 푥푥 in the second equation is –6.
2. 4x²=1024

Solution:

4 푥푥^2 = 1024

4푥푥

2 4 =

1024 4

푥푥^2 = 256

√푥푥^2 =√ 256

√푥푥∙푥푥=√ 16 ⋅ 16

푥푥= ± 16

(^) √푥푥^2 = 36
Solution:
�푥푥^2 = 36
푥푥= ±36

Why is ─ 5 not a solution to x³= 125?

Solution: x³=125 has a solution of 5. When ─5 is cubed, the result is ─125, not 125.

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Date: ___

Math Task