# Rational functions question

• Dec 2nd 2012, 07:42 PM
skg94
Rational functions question
A rational function y= a/(x-7) +k passes through the points (10,1) and (2,9) find values of a and k.

How do i do this, i know how to find one of any value, a,h,k but not two
• Dec 2nd 2012, 08:13 PM
Prove It
Re: Rational functions question
Where did h come from? Your function is \displaystyle \begin{align*} y = \frac{a}{x - 7} + k \end{align*}, so there are only two parameters, a and k.

By substituting each of the two points into the equation, you will get two equations with a and k as unknowns. Solve them simultaneously.
• Dec 2nd 2012, 09:10 PM
skg94
Re: Rational functions question
how do i substitute both of them at the same time?

if 1=a/(10-7) + k

how do i find both?
• Dec 2nd 2012, 09:13 PM
Prove It
Re: Rational functions question
You don't. Substitute one point to give you the first equation, which you have done.

Then go back to the original equation and substitute the second point to give you the second equation.
• Dec 2nd 2012, 09:21 PM
skg94
Re: Rational functions question
i dont understand how can i just ignore one unknown value?
• Dec 2nd 2012, 10:24 PM
skg94
Re: Rational functions question
i got it thanks