SOLUTION: Find a quadratic model for the set of values: (-2, -20), (0, -4), (4, -20). Also please show your work, thanks.

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Find a quadratic model for the set of values: (-2, -20), (0, -4), (4, -20). Also please show your work, thanks.       Log On


   

Question 959687: Find a quadratic model for the set of values: (-2, -20), (0, -4), (4, -20).
Also please show your work, thanks.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
y=ax%5E2%2Bbx%2Bc
So then using the points,
-20=a%28-2%29%5E2%2Bb%28-2%29%2Bc
1.4a-2b%2Bc=-20
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-4=a%280%29%5E2%2Bb%280%29%2Bc
2.c=-4
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-20=a%284%29%5E2%2Bb%284%29%2Bc
3.16a%2B4b%2Bc=-20
Substitute for c in eq. 1 and eq. 3.
4a-2b-4=-20
4a-2b=-16
4.2a-b=-8
and
16a%2B4b-4=-20
16a%2B4b=-16
5.4a%2Bb=-4
Add eq. 4 and 5,
2a-b%2B4a%2Bb=-8-4
6a=-12
a=-2
Then from eq. 5,
4%28-2%29%2Bb=-4
-8%2Bb=-4
b=4
So,
y=-2x%5E2%2B4x-4
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