SOLUTION: how do i graph y=-x^2+2x+1

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Question 676328: how do i graph y=-x^2+2x+1
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
find the x intercepts, there will be two as indicated by x%5E2
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-%28x%5E2-2x-1%29+=+0
Use quadratic equation
x+=+%28-%28-2%29%2B-sqrt%28%28-2%29%5E2-4%281%29%28-1%29%29%29%2F%28%282%29%281%29%29%29
x+=+%282+%2B-+sqrt%284--4%29%29%2F%282%29
x+=+%282+%2B-+sqrt%288%29%29%2F2
x+=+%282+%2B-+2sqrt%282%29%29%2F2
x+=+1+%2B-+sqrt%282%29
x = 1 + sqrt%282%29 = 2.4
x = 1 - sqrt%282%29 = -.4
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Choose a couple of values for x and solve for y
x: -x%5E2%2B2x%2B1: (x,y)
3: -(3^2) + 2(3) + 1 = -9+6+1 = -2: Plot (3,-2)
2: -(2^2) + 2(2) + 1 = -4+4+1 = 1: Plot (2,1)
1: -(1^2) + 2(1) + 1 = -1+2+1 = 2: Plot (1,2)
0: -(0^2) + 2(0) + 1 = 0+0+1 = 1: Plot (0,1)
-1: -(-1^2) + 2(-1) +1 = -1-2+1 = -2: Plot (-1,-2)
-2: -(-2^2) + 2(-2) +1 = -4-4+1 = 1: Plot (-2,1)
-3: -(-3^2) + 2(-3) +1 = -9-6+1 = -14: Plot (-3,-14)
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graph%28300%2C200%2C-5%2C10%2C-20%2C5%2C-x%5E2%2B2x%2B1%29
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