Changing The Subject Of A Formula

Changing The Subject Of A Formula | Algebra | Maths | FuseSchool

In this video we look at how to change the subject of a formula. This is a very useful algebraic skill. It means we can rearrange a formula so that a different variable becomes the ‘subject’. The subject is the letter that’s on it’s own on the other side of the equals = sign. We change the subject to make the unknown variable the subject. To change the subject, we make use of opposites. Adding and subtracting are opposites, multiplying and dividing are opposites, and squaring and square rooting are opposites. Sometime we may also look to factorise or expand brackets. Then it’s just like solving equations: make use of these opposites and everything you do to one side, you must also do to the other side - we have to keep everything balanced. Take your time, moving one variable or number at a time. Just make sure you always remember to do the opposite to BOTH sides and cancel on the one side. And always start with the things that are ‘least’ connected to your chosen subject.