eMentor Message History

Simultaneous Equations
Message history

In this example, the student has sent a message to the eMentor asking for help with Simultaneous Equations

Parul Student @ 18 Feb 08 09:39 I am stuck on simultaneous equations.

Not sure how to do it.

Please help

Terry eMentor @ 18 Feb 08 09:45 Simultaneous Equations are equations with two unknowns.

In order to solve them there are two different methods.

You can use either method.

Method 1 is Elimination

Method 2 is Substitution

If you give me an example then I can talk you through it .

Messages on the same topic may go back and forth between you and an eMentor over a number of hours/days

Parul Student @ 18 Feb 08 09:50 x + y = 3 and

2x + 3y = 8

It asks us to solve it.

Not sure where to begin.

Our Coaches are experienced at taking you through a problem step by step

Terry eMentor @ 18 Feb 08 09:57 'Solving' simultaneous equations means finding the values of 'x' and 'y' that make them true. The following steps will demonstrate how to solve simultaneous equations by the substitution method.

Using your example:

(1) Isolate one of the variables ( ‘x’ ) on one side of one of the equations:

x + y = 3

Isolating ‘x’:

x = 3 - y

(2) Substitute for the isolated variable in the other equation:

2x + 3y = 8

Substituting 3 - y for ‘x’:

2(3 - y) + 3y = 8

This equation has only one variable, so we can solve it.

(3) Solve this equation for the other variable, ‘y’:

2(3 - y) + 3y = 8

Expanding the brackets:

6 - 2y + 3y = 8

Simplifying:

6 + y = 8

Subtracting 6 from both sides:

y = 2

(4) Substitute the known value of ‘y’ into the equation for ‘x’ derived in step 1:

x = 3 - y

Substituting 2 for ‘y’:

x = 3 - 2

Therefore:

x = 1


Does that help?

It might be a good idea to understand this method first.

Let us know how you get on.

Also, have you had a look at some of the resources within the content?

Parul Student @ 18 Feb 08 10:00 Yes, thank you I will follow that through.

I am not sure how to get to the content.

Could you tell me.


The Coaches will recommend suitable resources for you to look at to reinforce the help they have given you

Terry eMentor @ 18 Feb 08 10:13 If you go into the Menu , there will be an option called 'CONTENT' .

If you then follow the path below :


'Edexcel GCSE in Mathematics (Linear) > Foundation > Number and algebra > Equations, Formulae and Identities > Equations'

you will be taken to some excellent multimedia interactive study/revision material.

Let us know how you get on. Good Luck.