what value of c makes x^2-24x+c a perfect sqaure trionomial? A.-144 B.-48 C.48 D.144 Need help asap please! Thank You?

x² - 24x + c
= (x² - 24x) + c
= [x² - 2(12)x + 12²] - 12² + c
= (x - 12)² + (c - 144)

It is a perfect square when (c - 144) = 0
Then, c = 144

...... The answer is : D. 144

c = -12
Reason
x^2 - 24x + (-12)^2 = >
x^2 - 24x + 144 =>
( x - 12)( x - 12) =>
(x - 12)^2

to find the constant to make a perfect square trinomial when you have an expression in the form of:

x² + bx

take half of "b", then square it.

So in your case, b is -24, so half is -12. Square that to get 144.

so: c= 144 (answer D)