Answer:
x = - 1, x = 8
Step-by-step explanation:
Given
x² - 7x - 8 = 0 ( add 8 to both sides )
x² - 7x = 8
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(- [tex]\frac{7}{2}[/tex] )x + [tex]\frac{49}{4}[/tex] = 8 + [tex]\frac{49}{4}[/tex] = [tex]\frac{81}{4}[/tex]
(x - [tex]\frac{7}{2}[/tex] )² = [tex]\frac{81}{4}[/tex] ( take the square root of both sides )
x - [tex]\frac{7}{2}[/tex] = ± [tex]\sqrt{\frac{81}{4} }[/tex] = ± [tex]\frac{9}{2}[/tex] ( add [tex]\frac{7}{2}[/tex] to both sides )
x = [tex]\frac{7}{2}[/tex] ± [tex]\frac{9}{2}[/tex]
Thus
x = [tex]\frac{7}{2}[/tex] - [tex]\frac{9}{2}[/tex] = [tex]\frac{-2}{2}[/tex] = - 1
x = [tex]\frac{7}{2}[/tex] + [tex]\frac{9}{2}[/tex] = [tex]\frac{16}{2}[/tex] = 8
