Substitution into common formulas
Mathematicians love to write formulae as algebraic shorthand for expressions that we would otherwise have to write as a sentence.
For example, instead of writing, "The area of a rectangle is calculated by multiplying the length by the breadth," I can write the algebraic formula $A=lb$A=lb. Much shorter right! Formulae also makes it easier to substitute values and evaluate equations.
There are lots of topics that have common formulae: simple interest, area, volume, perimeter and temperature conversions just to name a few. Make sure your familiar with the formulae for your topic before you start doing exercises.
Here are some examples to get you started.
Examples
question 1
The perimeter of a square with side lengths of $a$a is given by the formula $P=4\times a$P=4×a.
Find $P$P if the length of each side is $5$5 cm.
question 2
The area of a triangle is given by the formula $A=\frac{1}{2}$A=12$($(base$\times$×height$)$).
If the base of a triangle is $3$3 cm and its height is $10$10 cm, find its area.
Question 3
The simple interest generated by an investment is given by the formula $I=\frac{P\times R\times T}{100}$I=P×R×T100.
Given that $P=1000$P=1000, $R=6$R=6 and $T=7$T=7, find the interest generated.