# How do you find the equation of the quadratic function that passes through the points #(1, 2)#, #(9, -4)# and #(11, -7)#?

##### 1 Answer

Equation is

#### Explanation:

Let the equation be

**.........................(A)**

**.........................(B)**

and **.........................(C)**

Subtracting (A) from (B), we get **....................(D)**

and subtracting (B) from (C), we get **.................(E)**

Now double (E) and subtract from (D) and we get

and now putting values of

Hence quadratic equation is

graph{(40y+3x^2-83)((x-1)^2+(y-2)^2-0.1)((x-9)^2+(y+4)^2-0.1)((x-11)^2+(y+7)^2-0.1)=0 [-16.25, 23.75, -11.92, 8.08]}