The ability to rearrange formulas or rewrite them in different ways is an important skill in algebra.
You will be familiar with the formula for the area of a rectangle which states A = l × w. Here A is the area, l is the length and w is the width. In the form A = l × w, we say that A is the subject of the formula. Usually, the subject of a formula is on its own on the left-hand side. If you know the value of l and w then you can substitute directly to find A.
Changing the subject changes the form of the equation to display it in a different way. This is sometimes called the rearranging formula.
To rearrange a formula you may
Example: Make 𝑥 the subject of the formula of a + 3x = y - b
a + 3x = y - b
Subtract a from both sides
3x = y - b - a
Divide both sides by 3
If there are brackets included in the formula then it is easier if you expand them first. Remove any fractions by multiplying by the denominator/s
Example: Make 𝑥 the subject of the formula of a(x + y) = 2ay
Solution:
Example:
When changing the subject you start by collecting the term that you want on one side of the equation. In some cases, the required subject will appear more than once in the given formula. In these examples, we factorise the terms involving the subject before proceeding further.
Example:
If a formula contains a power or a root then this must be isolated before performing the inverse operation. It is important to remember that square and square root are inverse functions, similarly, cube and cube root.
Example:
The main topics in GCSE Maths are:
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Although many people think of GCSE maths as a difficult subject, with the correct training and preparation,you can master it in time. You can practice GCSE Maths topic-wise questions daily to improve speed, accuracy, and time and to score high marks in the GCSE Maths exam.
A grade of 4 or 5 would be considered "good" because the government has established a 4 as the passing grade; a grade of 5 is seen as a strong pass. Therefore, anything that exceeds this level would be considered good. You can practice GCSE Maths topic-wise questions to score good grades in the GCSE Maths exam.
You can get a high score in GCSE Maths through meticulous practice of GCSE Maths topic-wise questions and GCSE Maths past papers.
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