Question about quadratic formula/parabolas
The question is:
A parabola has zeros -6 and 2 and y-intercept -9.
a) Write its equation in factored form, expanded form and vertex form.
b)Use the expanded form and the quadratic formula to verify that the zeros are -6 and 2.
First, to write the equation in factored form I substituted y=-9, x=0 to find a.
Which therefore made the equation in factored form:
And it was therefore in expanded form:
However, in checking the zeros of this equation with the quadratic formula,
I could not get -6 and 2 for the zeros.
x=-bħsquare root of b^+4ac/2a
x=-3ħsquare root of 3x3+4(3/4)(-9)/2a
x=-3ħsquare root of 9-27/2a
x=-3ħsquare root of -18 /2a
Already I know that this is wrong.
I must email this to my teacher before the end of the week.