Question

Use completing the square to solve the equation x2 - 10x = -8.

Answer 1

Answer:

x^2 - 10x + 25 = 17

Step-by-step explanation:

Please use " ^ " to denote exponentation:

x^2 - 10x = -8

x^2 - 10x + 25 = 17

x^2 - 10x + 25 = -8

x^2 - 10x - 25 = -33

Begin with x^2 - 10x = -8.  Here's the process for completing the square:

1.  Take half of the coefficient of x and square the result:

    (1/2)(-10) = -5, and then (-5)^2 = + 25

2.  Add this 25 to the first two terms of x^2 - 10x = -8 and also to the      constant -8:    x^2 - 10x + 25 = -8 + 25, or     x^2 - 10x + 25 = 17

3.  Match this result to one of the given possible answers.  Turns out that the given possible answer matching our result is the first one:

x^2 - 10x + 25 = 17