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?
回答 (3)
2016-07-20 8:40 pm
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
= (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
2016-07-20 8:41 pm
c = -12
Reason
x^2 - 24x + (-12)^2 = >
x^2 - 24x + 144 =>
( x - 12)( x - 12) =>
(x - 12)^2
Reason
x^2 - 24x + (-12)^2 = >
x^2 - 24x + 144 =>
( x - 12)( x - 12) =>
(x - 12)^2
2016-07-20 8:41 pm
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)
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)
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