Solve $x ^ { 2 } - 8 x - 9 = 0$ by completing the square, if possible.
A) $x = - 1 , x = 9$
B) $x = 8 , x = - 9$
C) $x = 1 , x = - 9$
D) $x = - 8 , x = - 9$
E)no solutions

Question

Quizplus · Accepted Answer

To solve the equation $x^2 - 8x - 9 = 0$ by completing the square, we first move the constant term to the other side: $x^2 - 8x = 9$. Then, we add $(\frac{-8}{2})^2 = 16$ to both sides to complete the square: $x^2 - 8x + 16 = 25$. This gives us $(x - 4)^2 = 25$. Taking the square root of both sides gives $x - 4 = \pm5$, leading to $x = 4 + 5 = 9$ and $x = 4 - 5 = -1$.

Solve x2−8x−9=0x ^ { 2 } - 8 x - 9 = 0x2−8x−9=0

Solve $x ^ { 2 } - 8 x - 9 = 0$