SOLUTION: convert quadratic polynomial y(x)=x^2-6x+7 into vertex form [completeting full sqaure];find Xv,Yv, y-intercept, x-intercept and graph it.

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Question 117705: convert quadratic polynomial y(x)=x^2-6x+7 into vertex form [completeting full sqaure];find Xv,Yv, y-intercept, x-intercept and graph it.
Found 2 solutions by josmiceli, edjones:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
y%28x%29+=+x%5E2+-+6x+%2B+7
Find roots
x%5E2+-+6x+%2B+7+=+0
x%5E2+-+6x+=+-7
complete the square by taking half of the -6, square it,
then add it to both sides
x%5E2+-+6x+%2B+9+=+-7+%2B+9
%28x+-+3%29%5E2+=+2
x+-+3+=+0+%2B-sqrt%282%29
x+=+3+%2B+sqrt%282%29
x+=+3+-+sqrt%282%29
The roots (x-intercepts) are at (3 + sqrt%282%29, 0) and (3 - sqrt%282%29,0)
The vertex is exactly between them at (3, y). What is y?
y%28x%29+=+x%5E2+-+6x+%2B+7 make x=3
y%283%29+=+3%5E2+-+6%2A3+%2B+7
y%283%29+=+9+-+18+%2B+7
y%283%29+=+-2
So, the vertex is at (3,-2)
Lastly, where is the y-intercept? It is where x=0
y%28x%29+=+x%5E2+-+6x+%2B+7
y%280%29+=+0%5E2+-+6%2A0+%2B+7
y%280%29+=+7
The y-intercept is at (0,7)
Here's the graph
+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+x%5E2+-+6x+%2B+7%29+

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
y(x)=x^2-6x+7
=x^2-6x+9-9+7 complete the square.
=(x-3)^2-2
y=a(x-h)^2+k
a=1, h=3, k=-2
Vertex=(h,k)=(3,-2)=(Xv,Yv)
.
the y intercept=y(0)=7
.
the x intercepts=
x^2-6x+7=0
(x-3)^2-2=0 See above.
(x-3)^2=2
x-3=+-sqrt(2) Take sqrt of both sides.
x=3+-sqrt(2) the x intercepts.
.
Ed
graph%28500%2C500%2C-10%2C10%2C-10%2C10%2Cx%5E2-6x%2B7%29