## Wednesday, May 6, 2009

### Solving Simultaneous Equations using Matrices

Did this topic in my 5KA class today. Had to rush thru a little bit coz this topic will be included in the mid year exam which will start next Monday.Very happy to see most of them are able to solve the problems given. I was told by my students that Datin Lee taught them this topic when I was away. Thank you Datin for making my job easier. Gave them some homework from the textbook. Hope they will complete it by the next class coz I really need to rush to cover the topic for the midyear exam. I consider the 5KA girls my special girls and I really hope they can do well in their exam. These are the things that were done in class today

Simultaneous equations can also be solved using matrices

Example:

Using matrices, calculate the values of x and y for the following simultaneous equations:

2x – 2y – 3 = 0

8 y = 7x + 2

Solution:

Step 1: Write the equations in the form ax + by = c

2x – 2y – 3 = 0 ⇒ 2x – 2y = 3

8y = 7x + 2 ⇒ 7x – 8y = –2

Step 2: Write the equations in matrix form.

Step 3: Find the inverse of the 2 × 2 matrix.

Determinant = (2 × –8) – (–2 × 7) = – 2

Step 4: Multiply both sides of the matrix equations with the inverse

So, x = 14 and y = 12.5