Question 730504
What is the quadratic function that contains the points
 (0, 121), (1,116) & (2,101)?
:
Using the form; ax^2 + bx + c = y; find a b and c
The first pair x=0, therefore we know that c = 121
Write equations for the other two pair
1, 116
1^2*a + 1b + 121 = 116
a + b = 116 - 121
a + b = -5
and
2, 101
2^2*a + 2b + 121 = 101
4a + 2b = 101 - 121
4a + 2b = -20
simplify divide by 2
2a + b = -10
:
Use elimination
2a + b = -10
a + b = - 5
--------------subtraction eliminates b, find a
a = -5
Find a
-5 + b = -5
b = 0
:
The equation: y = -5x^2 + 0b + 121 or just
y = -5x^2 + 121
:
Check this using the given x/y pairs