- #1

DDRchick

- 27

- 0

**Find an equation of a rational function f(x)that satisfies the conditions. We're allowed to use a calculator, by the way. (:**

Okay, conditions:

vertical asymptote: x=-5, x=0

Horizontal asymptote: y=0

x-intercept=7; f(1)=4

**On the test i had no idea how to do it, but after seeing her key,I somewhat understand.**I looked in the textbook and was able to see where many things came from.

a(x-7)/(x+5)(x)

for one, i have no idea where the a and the x came from. I do, however, understand that the (x-7) is from the x-int. and that the (x+5) is from the v.a.

4=a(1-7)/(1+5)(x) again, no idea where the a and x came from. I see that 4=f(1) which means that y=4 and x=1.

4=a(-6)/(6)(1)

I understand she plugged in that last x finally with a 1 and simplified everything else.

4=-a, a=-4

f(x)=-4(x-7)/x(x+5)

I understand the final equation. I'd just love to know were she got that a and the x (by iself on the denominator) from! Thanks (: