Question

Which one?
A. B. C. Or D.​

Answer 1

D) {1, -1}

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.

Answer 2

D

Explanation:

Given

a² - 1 = 0 ( add 1 to both sides )

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

a = ±
`√(1)` = ± 1

solution is { 1, - 1 } → D