# Math Help - Algebra in Pre-Calc

1. ## Algebra in Pre-Calc

If f(x)=(x-B)/(x=A) and f(2)=0 and f(1) is undefined what is A and B?

2. If f(2) is 0 then that means the top is 0 so 2 - B is 0. Which means B is ...?

If f(1) is undefined, that means the bottom is 0 so whatever the bottom was supposed to be is 0, which means A is ...?

3. Originally Posted by Voluntarius Disco
If f(x)=(x-B)/(x=A) and f(2)=0 and f(1) is undefined what is A and B?
You meant $f(x)=\frac{x-B}{x-A}$, right? I'm assuming the
"=" was a mistake.

We know that: $f(2)=\frac{2-B}{2-A}=0$ and that $f(1)=\frac{1-B}{1-A}$ is undefined. If f(1) is undefined, that means that we will be dividing by zero, such that $A=1$.

We can now substitute A for 1:

$f(2)=\frac{2-B}{2-1}= 0$

$2-B=0$

$B=2$

4. B=2, A=1? That's what I have as answers but I'm just checking.