Question 523333: Can you graph T=-.2x^2+12x+11
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! Can you graph T=-.2x^2+12x+11
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T=-.2x^2+12x+11
complete the square
T=-.2(x^2-60x+900)+11+180
T=-.2(x-30)^2+191
you now have one point to plot, the vertex at (30/191)
To find two additional points set T=0, and find the x-intercepts
0=-.2(x-30)^2+191
.2(x-30)^2=191
(x-30)^2=191/.2=955
take square root of both sides
x-30≈±√955≈±30.9
x≈60.9
and
x≈-0.9
..
You now have three points with which to plot the given equation: (30,191), (-0.9,0) and (60.9,0)
..
note: you could have used the quadratic formula to find the x-intercepts, but for this type of problem it is easier to use completing-the-square method
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