Question

Fill in the missing term so that the quadratic equation has a graph that opens up, with a vertex of
(– 3, – 25), and x intercepts at x = -8 and x = 2. (Do not include the negative sign in your answer.)

y = x2 + 6x − ___

Answer 1

tmi

Answer 2

if the vertex is (-3,-25) you can write
\[-25=(-3)^2+6\times (3)+c\] and solve for c

Answer 3

or you could write
\[0=(-8)^2+6\times (-8)+c\] and solve for c

Answer 4

for that matter you can write
\[y=(x+8)(x-2)\] multiply out and find c. that may be easiest.
\[y=x^2+6x-16\]

Answer 5

in fact the very very simplest way to do it is take the zeros, -8 and 2, and multiply them together to get
\[c=-16\]