Question 440153: Write the quadratic function in the vertex form.
y = x2 - 20x
A. y = (x + 20) 2 - 20
B. y = (x - 20) 2 - 400
C. y = (x - 10) 2 - 100
D. y = (x + 10) 2 - 10
Answer by rapaljer(4671) (Show Source):
You can put this solution on YOUR website! In order to "complete the square on x^2-20x, you have to take HALF of the coefficient of -20x which would be -10. The only answer that has (x-10)^2 is C. Moreover, if you expand (x-10)^2 -100, you get x^2-20x, which is correct!!
Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
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