# Simultaneous equations problem

• August 19th 2012, 04:13 PM
william24
Simultaneous equations problem
How to use the method of substitution to solve the following simultaneous equation?
http://www.eso.org/sci/software/esom...vola/img49.gif3x+10y=51
x-y/2=11/2
What are the following steps?
• August 20th 2012, 12:24 AM
earboth
Re: Simultaneous equations problem
Quote:

Originally Posted by william24
How to use the method of substitution to solve the following simultaneous equation?
http://www.eso.org/sci/software/esom...vola/img49.gif3x+10y=51
x-y/2=11/2
What are the following steps?

Determine y in the 2nd equation:

$x-\frac y2=\frac{11}2~\implies~\boxed{y=2x-11}$ [A]

Now replace y by the term 2x-11 in the 1st equation:

$3x+10y=51~\implies~3x+10(2x-11)=51~\implies~23x = 161~\implies~x=7$

Now re-substitute the value of x into the equation [A] to get the value of y.