The subject of an equation/a formula is a variable that is expressed in terms of other variables. It should have an exponent of 1 and a coefficient of 1.

Checking and securing understanding of changing the subject

Maths

In this unit, pupils learnt to solve quadratic equations by factorising and this skill will be required in the future unit through manipulating two simultaneous equations to find the solutions. For pupils studying the higher content, solving quadratic equations is required if one of the simultaneous equations is a quadratic.

In the prior unit, pupils used the distributive law to find the product of two binomials. In algebraic manipulation, pupils use apply this knowledge in order to factorise quadratics.

Algebraic manipulation

Make $$x$$ the subject of $$3y - x = 15$$

Make $$y$$ the subject of $$4x + 2y = 8$$

Make $$z$$ the subject of $$\frac{z}{2} + 3x = 7$$

Make $$a$$ the subject of $$b = 3(a - 4) + 2$$

Make $$m$$ the subject of $$\frac{4m + 5}{3} = n$$

Make $$p$$ the subject of $$2p + \frac{q}{3} = 4$$

If the side of an equilateral triangle is $$3n+1$$, write an expression for the perimeter. 

If the side of a regular pentagon is $$14y - a$$ write an expression for the perimeter. 

Which of the following is an expression for the area of a square with side length $$3x$$

What is the value of $$x$$ for $$5(x + 7) = 30$$?

If $$x$$ is a positive integer, what is the value of $$x$$ for $$x^2 - 4 = 0$$?

What is the value of $$x$$ for $$2x - 3 = 7$$?

This lesson will soon be taken down.

Checking and securing understanding of changing the subject

Lesson outcome