# With the following coordinates (16,46) (18,64) (20,60) create three formulas using Y+Ax^2+Bx+C

then solve for A,B, and C to form the final equation.

## (16)^2 a + (16) b + c = 46

(18)^2 a + (18) b + c = 64

(20)^2 a + (20) b + c = 60

is

256 a + 16 b + 1 c = 46

324 a + 18 b + 1 c = 64

400 a + 20 b + 1 c = 60

you can solve that by substitution or elimination but I go to a Gauss Jordan calculator

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

and I get

a = -11/4

b = 205/2

c = -890