SOLUTION: (-4,-37) (2,11) (0,-1) I need to write a quadratic, mostly I'm confused about the triple elimination part of it.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: (-4,-37) (2,11) (0,-1) I need to write a quadratic, mostly I'm confused about the triple elimination part of it.       Log On


   

Question 259563: (-4,-37) (2,11) (0,-1)
I need to write a quadratic, mostly I'm confused about the triple elimination part of it.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
y=ax%5E2%2Bbx%2Bc
1.-37=16a-4b%2Bc
2.11=4a%2B2b%2Bc
3.-1=0a%2B0b%2Bc
It's more straightforward that you thought.
From eq. 3,
c=-1
Substitute into 1 and 2.
16a-4b-1=-37
16a-4b=-36
4.4a-b=-9
.
.
4a%2B2b-1=11
4a%2B2b=12
5.2a%2Bb=6
Add 4 and 5 together,
4a-b%2B2a%2Bb=-9%2B6
6a=-3
a=-1%2F2
.
.
.
4a-b=-9
4%28-1%2F2%29-b=-9
-2-b=-9
b=-2%2B9=7
+a=-1%2F2
b=7
c=-1
y=-%281%2F2%29x%5E2%2B7x-1