Let's use an example.
x+y=6
2x+3y=14
Find the values of x and y.
When I was kid back then, I was always wondering why are equations important? Well, for me, its because we want to be precise with our asnwers.
x+y=6. There are many answers to this. Including:-
4+2
3+3
even 7+(-1)
therefore, what method should we use to ensure our calculation is accurate?
well, we have 2 equations. lets remove one variable out of the picture so we are left with only one
at the beginning, x+y=6 ......equation 1
2x+3y=14........equation 2
now, we decided to remove either x or y because removing either one of them will make it so much easier to find a specific value for x or y.
to do this, let's decide to remove x as an example.
multiplying equation 1 by 2 gives us,
2x+2y=12.....set this to equation 3
remember equation 2? 2x+3y=14
it can be seen now that we can remove 2x by performing equation 3-equation2 which gives us:-
y=2
we now have a value for y which is great so let's find value x by placing y=2 into equation 1, 2 or 3 since we already have a value.
let us take equation 1 in this case.
x+y=6
y=2, therefore, x+2=6
and x=6-2
=4
and this, x=4 and y=2
to check our answers, we can place the values of x and y into any equations to find whether out answers match.
using equation 3,
2x+2y=12
2(4)+2(2)=8+4=12
and this is how we know our answers are correct!