# How do you write a quadratic equation with vertex (-1, 4) and point (-3, - 4)?

##### 1 Answer

Apr 8, 2016

#### Explanation:

The quadratic equation in vertex form is :

#y=a(x-h)^2+k # where (h,k) are the coords of the vertex and a is a constant.

here the vertex = (-1,4) , so we can write

# y = a(x+1)^2 + 4" and to find a , use (-3,-4")# substitute x = -3 and y = -4 into the equation.

hence:

#a(-3+1)^2 +4 = -4 #

#rArr 4a+4 = -4 → 4a = -8 → a = -2 # thus the equation is :

# y=-2(x+1)^2 + 4 # or by expanding the bracket we could also have.

# y = -2(x^2+2x+1)+4 → y = -2x^2 - 4x +2 #