Question

The parabola y=ax^2+bx+3 has a vertex (-2,-1) find a and b

Answer 1

Some one help!

Answer 2

The standard equation of parabola = y = ax 2 + bx + c
And the vertex, x co-ordinate = x = -b/2a okay?
And we have a point on the parabola = (x,y) = (-2,-1)
And so
-1 = 4a - 2b + 3 or
4a - 2b = -4 ---- 1
x = -b/2a
-2(2a) = -b
-4a = -b --- 2
Use the 2 equations understood? :)

Answer 3

Refer to this if you have any doubt!
http://www.mathwarehouse.com/geometry/parabola/standard-and-vertex-form.php

Answer 4

Are you getting me?

Answer 5

ok thanks!

Answer 6

:)