Question

What number needs to be added to both sides of the equation to complete the square?
x^2-9x=8

Answer 1

$\frac{81}{4}$

since the coefficient of the x² term is 1 then add

($\frac{1}{2}$ the coefficient of the x-term )² to both sides

x² + 2(- $\frac{9}{2}$ )x + $\frac{81}{4}$ = 8 + $\frac{81}{4}$