Did you notice that two of the points have the same y value of -20
so the vertex must lie on x = 1 midway between the two x's , (because (-2 + 4)/2) = 1 )
So, let the quadratic be
y = a(x-1)^2 + c
for the point (0,-4)
-4 = a + c
for the point (4,-20)
-20 = 9a + c
subtract them:
-16 = 8a
a = -2
plug into -4=a+c
-4 = -2+c ----> c = -2
the quadratic is : y = -2(x-1)^2 - 2
Find a quadratic model for the set of values: (-2, -20), (0, -4), (4, -20). Show your work
Please help!
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1 answer