SOLUTION: Given (-1,-2) (1,-4) (2,4) find the equation of the quadratic equation. f(x)=ax^2+bx+c -2=a(-1)^2+b(-1)+c -4=a(1)^2+b(1)+c 4=a(2)^2+b(2)+c -2=a-b+c -4=a+b+c 4=4a+2b+c ?

Question 1009091: Given (-1,-2) (1,-4) (2,4) find the equation of the quadratic equation.
f(x)=ax^2+bx+c
-2=a(-1)^2+b(-1)+c
-4=a(1)^2+b(1)+c
4=a(2)^2+b(2)+c
-2=a-b+c
-4=a+b+c
4=4a+2b+c
???????
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
You made the correct system of equations, .

Next, choose either row-reduction matrix operations; or elimination method, or substitution method.

Substitution method is the least advanced way, and as a start, take E1, solve for c:

and substitute into E2 and E3:

-
, which shows one of the coefficients, easily allowing for finding another by using that other's now known value...

, and obviously just found as well, .

You still want to find the value for c. Use any equation of the system that you want.
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