SOLUTION: the parabola y=ax2+k passes through the points (-1,3) and (3,-13). find the values of a and k

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Question 907608: the parabola y=ax2+k passes through the points (-1,3) and (3,-13). find the values of a and k
Answer by reviewermath(1029) About Me  (Show Source):
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the parabola y=ax%5E2%2Bk passes through the points (-1,3) and (3,-13). find the values of a and k.
Equation 1: a%28-1%29%5E2+%2B+k+=+3
Equation 2: a%283%29%5E2+%2B+k+=+-13
Subtract the 1st equation from the 2nd equation, the result is
8a+=+-16, divide both sides by 8
a = -2, substitute into Equation 1 and solve for k:
-2 + k = 3
k = 5
Answers: a = -2 and k= 5