Question

solve the quadratic equation x2 - x = 30 by completing the square

Answer 1

Answer:

A

Step-by-step explanation:

Given

x² - x = 30

To complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(- $\frac{1}{2}$)x + $\frac{1}{4}$ = 30 + $\frac{1}{4}$

(x - $\frac{1}{2}$)² = $\frac{121}{4}$

Take the square root of both sides

x - $\frac{1}{2}$ = ± $\sqrt{\frac{121}{4} }$ = ± $\frac{11}{2}$

Add $\frac{1}{2}$ to both sides

x = $\frac{1}{2}$ ± $\frac{11}{2}$, thus

x = $\frac{1}{2}$ - $\frac{11}{2}$ = - 5

x = $\frac{1}{2}$ + $\frac{11}{2}$ = 6