Change of Subject of Formulas Involving Addition, Multiplication, and Roots - JSS3 Mathematics Lesson Note

Changing the subject of a formula involves rearranging it to express a different variable as the subject. This is useful in solving problems where a different variable needs to be isolated.

Example 1: Changing the subject involving addition

Given the formula:

𝐴=𝐵+𝐶

To make 𝐵 the subject:

𝐵=𝐴−𝐶

Example 2: Changing the subject involving multiplication

Given the formula:

𝑃=𝐿×𝑊^2

To make 𝐿 the subject:

Multiply both sides by 2 to eliminate the fraction:

2𝑃=𝐿×𝑊

Divide both sides by 𝑊 to isolate 𝐿:

𝐿=2𝑃𝑊

Example 3: Changing the subject involving roots

Given the formula:

𝐴=𝐵+𝐶

To make 𝐵 the subject:

Subtract 𝐶 from both sides:

𝐴−𝐶=𝐵

Square both sides to eliminate the square root:

(𝐴−𝐶)^2=𝐵

𝐵=(𝐴−𝐶)^2

These examples illustrate how to manipulate formulas to isolate different variables, involving addition, multiplication, and roots.