the x intercetps are when the function hits the x axis or when y=0 or when the funciton equals zero
0=x^2-3x-28
solve
factor
wat multipliest o -28 and adds to -3?
-7 and 4
0=(x-7)(x+4)
0=x-7
7=x
0=x+4
-4=x
the x intercetps are at x=-4 and x=7 or (-4,0) and (7,0)