GCSE Mathematics/Simultaneous Equations
Solving simultaneous equations[edit | edit source]
By elimination[edit | edit source]
One way of solving a simultaneous equation is by canceling out either the x or y values so that you are left with a linear equation.
First example[edit | edit source]
In this example, we could subtract the second equation from the first to get this:
Once we know this, we can go back to one of the original equations, and replace y with 5, then solve it, like this:
So, the final solution is:
Second example[edit | edit source]
We can see that in this example the equations will not cancel each other out. To make them cancel each other out, we multiply the second equation by two and get:
We can now subtract this from the original equation in order to get a linear equation that we can solve:
Now that we know the value of x, we can substitute it in the first equation in order to solve it:
So, the final solution is: