Find a quadratic function to model the values in the table

Question

Table: 

 

x | y

-----

-2|-18

0 | -4

2 | -14

Answer 1

Write the quadratic equation in standard form:

 

y = ax² +bx +c     (1) 

 

Plug x-s from the table into  (1). You will have:

 

c = -4

 

4a - 2b + c = -18

 

4a + 2b + c = -14

 

By solving thios system you will obtain   a = -3,  b = 1. Thus

 

y = -3x² + x - 4

 

This expression holds all values of x and y in your table.