## Algebraic Formulae

3.1  Algebraic Formulae

 Definition It is written in the form of an equation that combines an algebraic expression using addition, subtraction, multiplication or division.

Forming formula

Example

1.  $$y= 3x -5$$

2.  $$w = \dfrac{6-v}{v}$$

3. $$L = \dfrac{1}{2} th$$

4.  $$A = \pi r^2$$

Changing the subject of the formula

 Tips The subject of the formula is represented by a letter. The subject of the formula should be on the left side of the equation.

Example

Determining the value of the variable

 Tips The value of a variable in the subject of the formula can be obtained when the value of other variables is given.

Example

Given $$Q= \dfrac{2v}{-v +u}$$, calculate the value of $$u$$, where $$v=2, Q= 4$$.

\begin{aligned} \\\space4 &= \dfrac{2(2)}{-2 + u} \\\\ 4 (-2 +u) &= 4 \\\\ -8 + 4u &= 4 \\\\ 4u &= 12 \\\\ u &= \dfrac{12}{4} \\\\ u &=3. \end{aligned}

Solving problems

 Tips It involves changing the subject of a formula, a combination of basic mathematical operations, square and square root.

## Algebraic Formulae

3.1  Algebraic Formulae

 Definition It is written in the form of an equation that combines an algebraic expression using addition, subtraction, multiplication or division.

Forming formula

Example

1.  $$y= 3x -5$$

2.  $$w = \dfrac{6-v}{v}$$

3. $$L = \dfrac{1}{2} th$$

4.  $$A = \pi r^2$$

Changing the subject of the formula

 Tips The subject of the formula is represented by a letter. The subject of the formula should be on the left side of the equation.

Example

Determining the value of the variable

 Tips The value of a variable in the subject of the formula can be obtained when the value of other variables is given.

Example

Given $$Q= \dfrac{2v}{-v +u}$$, calculate the value of $$u$$, where $$v=2, Q= 4$$.

\begin{aligned} \\\space4 &= \dfrac{2(2)}{-2 + u} \\\\ 4 (-2 +u) &= 4 \\\\ -8 + 4u &= 4 \\\\ 4u &= 12 \\\\ u &= \dfrac{12}{4} \\\\ u &=3. \end{aligned}

Solving problems

 Tips It involves changing the subject of a formula, a combination of basic mathematical operations, square and square root.