Answer:
D
Step-by-step explanation:
Given
a² - 1 = 0 ( add 1 to both sides )
a² = 1 ( take the square root of both sides )
a = ± [tex]\sqrt{1}[/tex] = ± 1
solution is { 1, - 1 } → D
D) {1, -1}
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.
