Question

Follow the process of completing the square to solve x2 - 10x + 8 = 0. What is the value of the constant that will be isolated on the right side of the equation in step 3? -8 -12 -32

Answer 1

25

Explanation:

Given the expression x^2 - 10x + 8 = 0.

According to completing the square method

Subtract 8 from both sides

x^2 - 10x + 8 - 8 = 0 - 8

x^2 - 10x = -8

Complete the square

Add the square of half of coefficient of x to both sides

Coefficient of x = -10

Half of Coefficient of x = -10/2

Half of Coefficient of x = -5

Square of Half of Coefficient of x = (-5)^2

Square of Half of Coefficient of x = 25

Add (-5)^2 to both sides

x^2 - 10x + (-5)^2 = -8 + (-5)^2

(x-5)^2 = -8 + 25

(x-5)^2 = 17

Hence the required constant that was added is 25