Question

Find the zeros of y = x^2 - 4x - 9 by completing the square.

A. x = -2 ± √13
B. x = 2 ± √13
C. x = ±3
D. x = 3 ± √13

Answer 1

Try this option:

x²-4x-9=x²-4x+4-13=(x-2)²-13=(x-2)²-√(13)²

it means, the answer is

$\left[\begin{array}{ccc}x=2- \sqrt13\\x=2+ \sqrt13\end{array}\right$