Question

Which equations are true for x = -2 and x = 2? Select two options

Answer 1

Answer:

A and C

Step-by-step explanation:

solving the equations

A

x² - 4 = 0 ( add 4 to both sides )

x² = 4 ( take square root of both sides )

x = ± $\sqrt{4}$ = ± 2 ← required solution

B

x² = - 4 ← has no real solutions

C

4x² = 16 ( divide both sides by 4 )

x² = 4 ( take square root of both sides )

x = ± $\sqrt{4}$ = ± 2 ← required solution

D

2(x - 2)² = 0 , then

x- 2 = 0 ( add 2 to both sides )

x = 2 ← not the required solution

Answer 2

Answer:

Answer A and C

Step-by-step explanation:

Let us solve the equations one by one and let us check whether the answers are matching with the answers given in the questions.

A) x² - 4 = 0

   ( x² - 2² ) = 0

   ( x -2 ) ( x + 2 ) = 0

   ∴ x - 2 = 0                   or           x + 2 = 0

      x = 2                                       x = -2               ( Matched )

B) x² = -4

  x = ±√-4  ← no real solutions                    (Not matched )

B)   3x² + 12 = 0

      3 ( x² + 4 ) = 0

      3 ( x² + 2² ) = 0 ← no real solutions      (Not matched)

C) 4x² = 16

Divide both sides by 4.

 x² = 4

 x = ±√4

 ∴ x = 2         or        x = -2       (Matched)

 D) 2 ( x - 2 )² = 0    

      (2x - 4)² = 0

      4x² - 16x + 16 = 0

Divide the whole equation by 4.

   x² - 4x + 4 = 0

 x² - 2x - 2x + 4 = 0

x ( x - 2 ) - 2 ( x - 2 ) = 0

( x - 2 ) ( x - 2) =

∴ x - 2 = 0          or        x - 2 = 0

  x = 2                            x = 2                 ( Not matched )