Dimitri is solving the equation x^2 - 10x = 21. which value must be added to both sides of the equation to make the left side a
perfect-square trinomial?
0
4
25
100

25

Step-by-step explanation:

Given

x² - 10x = 21

To complete the square on the left side

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

x² + 2(- 5)x + 25 = 21 + 25, that is

(x - 5)² = 46

6, 10

9, -13

12, -21

18, -23

step-by-step explanation:

you just add 6 to the x-coordinate and subtract 10 from the y-coordinate.