Cramer's Rule

Hi everyone.
I have discovered another way to solve simultaneous equations using matrices.
It's called the Cramer's Rule.


Look at the following example to study how Cramer's Rule is used to solve the simultaneous equations below:-

5x + 3y= −11

2x + 4y = −10

Worked solution

D = det of

5 3
2 4

= 20 − 6 = 14


Dx = det of

−11 3
- 10 4

= −44 + 30 = −14


Dy = det of

5 −11
2 -10

= −50 + 22 = −28

Therefore,

x = Dx/D = −14/ 14 = −1

and y = Dy/D = −28/14 = −2


Now it's your turn to use Cramer's Rule to solve the following simultaneous equations.

- x + 5y = 4

2x + 5y = - 2


Work out D, Dx and Dy and then the solutions x and y. Post these as your comments. You have until 10 Feb to do this.

Matrices and Solving Linear Equations

Solving simultaneous linear equations using matrices.


Solve - x + 5y = 4
2x + 5y = - 2

by matrix method.



By posting your answers as comments, write about the following.

What do you need to do to solve the simultaneous equation above using matrices?

Work out the answers to x and y.

Do this by 7 Feb.

Are you okay with matrices?

Hello, we have learnt matrices together in class and now I hope you will take the following quiz on matrices to check how well you have learnt the topic.


1) When adding matrices of the same orders/dimensions, will the answer have the order/dimension of the matrices?

2) When multiplying, do matrices need to be of the same orders/dimensions?

3) Can you multiply a matrix by something other than another matrix?

4) When adding matrices, do you add different positions together?


If any of your answers is a "no", please write to explain why you say so.


Post your answers to these 4 questions by 5 Feb.