Diego is solving the equation x2 – 12x = 21 Which value must be added to both sides of the equation to make the left side a perfect -square trinomial?

A

36

B

32

с

144

D

4

Step-by-step explanation:

Given

Required

Make a perfect square

First, get the coefficient (k) of x

Divide by 2

Square this result:

Hence, 36 when added to the left-hand side makes it a perfect square trinomial

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.