Question

Find a quadratic model for the set of values

x -2 0 4
f(x) 1 -3 85

A) y = 3x^2 + 6x - 4

B) y = -4x^2 - 6x + 3

C) y = 4x^2 + 6x - 3

D) y = 6x^2 + 4x - 3

Answer 1

C) y = 4x^2 + 6x - 3

Answer 2

just check by substitution of x and y

Answer 3

If this problem was not a multiple choice problem, you do it
that way
\[
f(x)= a x^2 + b x + c\\
f(-2)=4 a-2 b+c=1\\
f(0)=c=-3\\ f(4)=16 a+4
b+c=85

\]
Solve for a, b and c to get
{ a = 4, b= 6, c=-3}

Answer 4

Ok thanks both of you