Question

Solve the quadratic equation by completing the square method: $x^2+8x-9=0$

• A. $-9,-1$
• B. $2,1$
• C. $-9,1$
• D. $9,1$

Answer 1

The correct option is C $-9,1$

$x^2+8x-9=0$

$\Rightarrow x^2+2\times \left(4\right)\times x+16-25=0$

${(x+4)}^2=25$

${(x+4)}^2=5^2$

$x+4=\pm 5$

$\Rightarrow x=1$ and $-9$

Hence, the answer is $1,-9.$