Algebraic expressions are very useful because they can represent a truth that applies for different values of the letters. So, an architect may want a building to be twice as high as it is wide and may be willing to build different buildings as long as the dimensions are like this. So he could have the algebraic expression h=2w and then substitute in the value of w that applies to the building’s width to decide how high it can be. So, for instance if the width of the building is 15m, how high can he build it?

Worked Example

• If x=2 and y=3, find the value of:
  • 5x – 2y
  • 4y(1+x)

Exercise 1

Answers