Question

Completing the Square

Answer 1

Answer:

C.7, -2

Step-by-step explanation:

A quadratic equation is a polynomial of degree two. A quadratic equation is in the form:

ax² + bx + c = 0; where a, b, c are constants.

Quadratic equation can be solved using different methods, such as completing the square method, quadratic formula.

Solving the equation 2x² - 10x - 20 = 8 using completing the square:

2x² - 10x - 20 = 8

2x² - 10x = 28

Divide through by 2, to make the coefficient of x² to be 1:

x² - 5x = 14

Add to both sides, the square of half of the coefficient of x [i.e. (-5/2)² = 6.25]

x² - 5x + 6.25 = 14 + 6.25

(x - 2.5)² = 20.25

taking square root of both sides:

x - 2.5 = √20.25

x - 2.5 = ±4.5

x = 2.5 ± 4.5

x = 2.5 + 4.5; or x = 2.5 - 4.5

x = 7 or x = -2