SOLUTION: find the x-intercepts and y-intercepts f(x) = -x^2 +2x+15 The x-coordinates of the intercepts are x= ___

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Question 395575: find the x-intercepts and y-intercepts
f(x) = -x^2 +2x+15
The x-coordinates of the intercepts are x= ___
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

f(x) = -x^2 +2x+15

Finding x-intercepts when f(x)=0

 -x^2 +2x+15 = 0

x+=+%28-2+%2B-+sqrt%28+64+%29%29%2F%28-2%29=+%28-2+%2B-+8%29%2F-2+  |Using Calculator

x = -3, 5  |x-intercepts P(-3,0) and Pt(5,0)

Finding vertex

Using the vertex form of a parabola, y=a%28x-h%29%5E2+%2Bk where(h,k) is the vertex

f(x) = -x^2 +2x+15   |completing square to put into vertex form

f(x) = -[(x-1)^2 -1] + 15

f(x) = -(x-1)^2 +1 + 15

f(x) = -(x-1)^2 + 16  Vertex is Pt(1,16)