Question

What are the x-intercepts of f(x)= 8/9(x^2+11x-80)

Answer 1

for x-intercepts put f(x)=0 (i.e if y=f(x) we are using y=0)
thus we have x^2+11x-80=0
and then solve using quadratic equations formula to get the required intercepts

Answer 2

factorable.

Answer 3

x^2+11x-80=0
x^2+16x-5x-80=0
or x(x+16)-5(x+16)=0
or (x+16)(x-5)=0
thus x=-16 or 5
thus the graph of f(x) crosses x-axis at -16,0 and 5,0