Which one?
A. B. C. Or D.

D

Step-by-step explanation:

Given

a² - 1 = 0 ( add 1 to both sides )

a² = 1 ( take the square root of both sides )

a = ± = ± 1

solution is { 1, - 1 } → D

D) {1, -1}

Step-by-step explanation:

Please share the instructions for this problem:  Solve a^2 - 1 = 0, or find the roots of a^2 - 1 = 0.

Answer D is correct.  Try substituting 1 for a, and then -1 for a.  In both cases the given equation is true.

hello :

70y^8 + 30y^6 = 2 ( 35 y^8 + 15y^6)

the lenght is : 35 y^8

the width is : 15y^6