Math CentralQuandaries & Queries


Question from benjamin, a student:

hi math central. benjamin here. during class, i had problem with this topic. normally i wont have problems with math but this topic i just too hard for me. please help i am having exam and test next week on this topic

here is the question:
using substitution method, solve the simultaneous equation.


Hi Benjamin,

I want to illustrate with a different question.

using substitution method, solve the simultaneous equation.


I would first multiply both sides of the first equation by $x-2$ to get

\[y + 6 = \frac12 x - 1.\]

Solving for $y$ gives

\[y = \frac12 x - 7.\]

Substitute this value for $y$ into the second equation to get

\[\frac{x - 4}{\frac12 x - 7 + 7}=4.\]

Solve for $x.$

Cautionary note:

Make sure you verify your answer. For example in my problem we cannot have $x = 2$ or $y = -7$ or at least one of the original fractions would have a denominator of zero.


About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS