MYTUTOR SUBJECT ANSWERS

408 views

What is the best way to solve simultaneous equations?

The easiest way to solve simultaneous equations is to label the equations so you clearly follow them throughout.

For example, say you are asked to solve the unknowns for the simultaneous equations 3x-y=8 and 2x+y=7 

Label the first equation 1.) and the second 2.), like so:

1.) 3x-y=8 

2.) 2x+y=7

You now need to perform an operation to eliminate one of the unknowns from the equations. It is always easiest to elimate the unknown which has the same multiple in each equation.

So here, we would work to elimate y. Looking at the signs we can see that equation 1.) has a  negative y and 2.) a positive, so all we have to do to eliminate y is the add the equation 2.) to equation 1.), like so:

1.) + 2.) : 5x=15

Now, all you have to do is solve this like a regular equation, so by dividing 15 by 5 we get x=3.

The next step is substitute the known x value into either one of the original equations. I will use both here to show that either works:

1.) 3(3)-y=8

so 9-y=8, and hence y=1. 

2.) 2(3)+y=7

so 6+y=7, and again, y=1

It is always useful to substitute your first known variable into one equation, and then substitute both variables into the second, as a check to see if you are correct.

Lucy W. GCSE Biology tutor, IB Biology tutor, GCSE Maths tutor, GCSE ...

1 year ago

Answered by Lucy, a GCSE Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

510 SUBJECT SPECIALISTS

£24 /hr

Tom W.

Degree: Mathematics (Masters) - Warwick University

Subjects offered:Maths

Maths

“Third year Maths undergraduate, with experience teaching Maths from GCSE to first year.”

£18 /hr

Monika T.

Degree: Mathematics (Masters) - Exeter University

Subjects offered:Maths

Maths

“I'm a Maths student currently studying my first year in the University of Exeter. As a young student who just recently finished A levels and GCSEs, I can remember how stressful they can be and how much work is required for a good grad...”

£20 /hr

Anahita G.

Degree: Maths and Economics (Bachelors) - York University

Subjects offered:Maths, Science+ 3 more

Maths
Science
Economics
Chemistry
.TSA. Oxford.

“I am a maths and economics student at the University of York. I have always loved logical and analytical subjects, for example Maths and the Sciences. I also particularly enjoy economics as there are countless ways to analyse and conc...”

About the author

Lucy W.

Currently unavailable: for regular students

Degree: Bsc Biological Sciences (Bachelors) - Exeter University

Subjects offered:Maths, Spanish+ 1 more

Maths
Spanish
Biology

“I am currently studying Biological Science at Exeter University - a course that I absolutely love.  I like to think I am a patient and considerate person, having experience tutoring younger family members, and other students whilst I ...”

You may also like...

Posts by Lucy

How do you explain the process of translation?

How is blood pumped around the body through the heart?

What is the best way to solve simultaneous equations?

Other GCSE Maths questions

How do I find the nth term of a sequence?

Sasha has a bag containing 12 red beads, and 8 blue beads. She draws one bead from the bag at random. What is the probability that it is blue?

Solve the equation ((2x+3)/(x-4))-((2x-8)/(2x+1))=1

What is 45% of 60?

View GCSE Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok