Past Questions: WASSCE Change Of Subject
In mathematics, we will study how to change a formula’s subject and determine the variable’s value.
Change a formula’s subject
The formula’s topic is:
It is a variable that the formula expresses in terms of other variables.
Formulas are written with a single variable—the formula’s subject—on the left-hand side of the equation. The rest of the equation is on the correct side. By replacing the literal numbers on the right side, we evaluate the formula.
For instance:
V is the subject in the equation v = u + at.
By changing the values of u, a, and t in the equation’s R.H.S., we may determine v in the example.
Changing the formula’s focus:
Start with the variable that will become the new subject of the formula, and use the inverse operation to solve equations in the reverse order of the order conventions.
1. To change the subject of the equation v = u + at to be “u,”
v – at equals u + at – at [remove from both sides at at]
v – at = u
also, u = v – at
2. To make “t” the formula’s subject, enter “v = u + at,”
at – u + v – u = u [take u away from both sides]
v – u = at
we obtain by dividing both sides by a:
(v – u) / a = a t / a
perhaps (v – u)/a = t
also try t = (v – u)/a