Question 21408
X^2 - 8 + 7 = 0
add 
-8+7=-1
{{{x^2}}}-1=0
factor;
(x+1)(x-1)=0
solve each side;
x+1=0
x=-1
x-1=0
x=1
so your answer;
x=-1 or x=1
hope you understand
=)