Question

3. A parabola y = ax2 +k passes through the points (-1,3) and (3, -13). Find the values of a and k.

Answer 1

plug the points to the equation
if you plug the point (-1,3) to the equation, you'll get :
equation 1 -> (3) = a(-1)^2 + k -> 3=a+k
then plug (3,-13), you'll get
equation 2-> (-13)=a(3)^2 + k -> -13=9a+k

then solve both equation by using substitution or elimination to get the value of a and k
you'll get a=-2 and k=5