Solve the simultaneous equations: 2x+2y=12 x-y=8 You must show your working

The first thing we want to do is change the first equation so it's either all x's or all y's, we don't want a mixture. Now looking at the bottom equation, we can rearrange it by adding y to both sides. This gives us x=8+y. It's important to remember these are simultaneous equations, that means we can substitute in (8+y) whenever it says x in the top equation.

Therefore the top equation is now 2(8+y)+2y=12 Let's expand out the brackets! 16+2y+2y=12 16+4y=12 4y=-4 y=-1

Now to work out x, we'll substitute -1 in whenever we see y in the bottom equation (the top would take longer to work out) x-(-1)=8 x+1=8 x=7

KA
Answered by Kasim A. Maths tutor

5005 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

3/5 of a number is 162. Work out the number.


Solve the pair of simultaneous equations {4x + y = 5, 3x - y = 2} using i) a graph and ii) an algebraic method


What is mathematics and why should I study it?


A ladder 7.4m long is leaning against a wall as shown in the diagram. The foot of the ladder is 2.9m away from the wall. Calculate the distance the ladder reaches up the wall to 2 significant figures.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences