Question

Find the equation for the cubic function, f(x), with roots at -5, 5 and -3, and has a y-intercept at (0, 2).

Answer 1

x^3+3x^2-25x+2

The concept here is that knowing the roots allow you to formulate the terms
y=(x+5)(x-5)(x+3)
however, you still need a constant term C in this equation
y=(x+5)(x-5)(x+3)+C
and you can find C by saying (x,y) =(0,2)
the constant C is not obvious, but you should know that it exists because when you plug in (0,2) into the y function without C, your function is invalid
thus, after you find C=77
expand the x and you will get
y=(x^2-25)(x+3)+77
y=x^3+3x^2-25x-75+77
y=x^3+3x^2-25x+2, which is your answer! GOOD JOB!

Answer 2

thanks

Answer 3

:D of course