Answer
The second step is wrong, and the correct answer is $x=-4\pm \sqrt{26}$.
Work Step by Step
The given equation is
$\Rightarrow x^2+8x=10$
Find the value of $(\frac{b}{2})^2$.
Substitute $8$ for $b$.
$=(\frac{8}{2})^2$
Simplify.
$=(4)^2$
$=16$
Add $16$ to each side of the equation.
$\Rightarrow x^2+8x+16=10+16$
Simplify.
$\Rightarrow x^2+8x+16=26$
Write the left side as the square of a binomial.
$\Rightarrow (x+4)^2=26$
Take the square root of each side.
$\Rightarrow x+4=\pm \sqrt{26}$
Subtract $4$ from each side.
$\Rightarrow x+4-4=-4\pm \sqrt{26}$
Simplify.
$\Rightarrow x=-4\pm \sqrt{26}$
Hence, the second step is wrong, and the correct answer is $x=-4\pm \sqrt{26}$.
