New
New
Year 11
Foundation

Checking and securing understanding of solving with simple algebraic fractions

I can solve equations involving simple algebraic fractions.

New
New
Year 11
Foundation

Checking and securing understanding of solving with simple algebraic fractions

I can solve equations involving simple algebraic fractions.

Lesson details

Key learning points

  1. The product of a number and its reciprocal is 1
  2. The product of a term and its reciprocal is 1
  3. Equivalence can be maintained by multiplying the connected statements by the same reciprocal.
  4. This step can help you simplify an equation so you can solve it.

Common misconception

When solving equations with fractional coefficients, pupils may divide by the reciprocal rather than multiply. E.g. $$\frac{1}{2}x = 8$$ pupils may just halve $$8$$

Start with integer coefficients, and get pupils used to the idea of multiplying by the reciprocal (not just dividing by the coefficient). This step should be written as part of the working. Answers can be checked by substitution.

Keywords

  • Solution - A solution to an equality with one variable is a value which, when substituted, maintains the equality between the expressions.

  • Reciprocal - The reciprocal is the multiplicative inverse of any non-zero number. Any non-zero number multiplied by its reciprocal is equal to 1

LC2 links well with solving right-angled trig equations. Pupils can use numerical examples such as $$\frac{12}{3} = 4$$ therefore $$\frac{12}{4} = 3$$ to help them see the multiplicative relationship $$\sin(x) = \frac{a}{b}$$ therefore $$b=\frac{a}{\sin(x)}$$.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Any non-zero number multiplied by its is equal to 1
Correct Answer: reciprocal
Q2.
What is the correct calculation to solve $$7x=8$$ in one step?
$$7x \times 7 = 8\times 7$$
$$7x = 8\times {1\over 7}$$
Correct answer: $$7x \times {1\over 7} = 8\times {1\over 7}$$
$$7x \times 8 = 8\times 8$$
$$7x \times {1\over 8} = 8\times {1\over 8}$$
Q3.
Match each number to its reciprocal.
Correct Answer:$$2$$,$$1\over 2$$

$$1\over 2$$

Correct Answer:$$1\over 2$$,$$2$$

$$2$$

Correct Answer:$$3\over 2$$,$$2\over 3$$

$$2\over 3$$

Correct Answer:$$-{1\over 2}$$,$$-2$$

$$-2$$

Correct Answer:$$-{2\over 3}$$,$$-{3\over 2}$$

$$-{3\over 2}$$

Correct Answer:$$1\over 6$$,$$6$$

$$6$$

Q4.
The solution to the equation $$4x + 8 = 12$$ is when $$x = $$ .
Correct Answer: 1
Q5.
What is the value of $$\frac{x-10}{5}$$ when $$x = 20$$?
Correct Answer: 2
Q6.
Match each expression containing brackets to its expanded form.
Correct Answer:$$2(3x-6)$$,$$6x-12$$

$$6x-12$$

Correct Answer:$$6(x-1)$$,$$6x-6$$

$$6x-6$$

Correct Answer:$$2(x-6)$$,$$2x-12$$

$$2x-12$$

Correct Answer:$$-6(-2-x)$$,$$6x+12$$

$$6x+12$$

Correct Answer:$$3(2x-6)$$,$$6x-18$$

$$6x-18$$

Correct Answer:$$6(3-x)$$,$$-6x+18$$

$$-6x+18$$

6 Questions

Q1.
The solution to the equation $${1\over 3}a = 6$$ is when $$a =$$ .
Correct Answer: 18
Q2.
Match each equation to its solution.
Correct Answer:$${1\over 4}a + 3 = 10$$,$$a = 28$$

$$a = 28$$

Correct Answer:$${1\over 4}(a + 3)=10$$,$$a = 37$$

$$a = 37$$

Correct Answer:$${4\over 7} a = 1$$,$$a = {7\over 4}$$

$$a = {7\over 4}$$

Correct Answer:$${7\over 4}a=14$$,$$a = 8$$

$$a = 8$$

Correct Answer:$$\frac{a+3}{7} = 2$$,$$a = 11$$

$$a = 11$$

Q3.
Match each expression to an equivalent expression.
Correct Answer:$${2\over 3}x$$,$$2x\over 3$$

$$2x\over 3$$

Correct Answer:$$2\over 3x$$,$$2({1\over 3x})$$

$$2({1\over 3x})$$

Correct Answer:$${2\over 3}\times {1\over 3x}$$,$$2\over 9x$$

$$2\over 9x$$

Correct Answer:$$2x \times {1\over 9}$$,$$2x\over 9$$

$$2x\over 9$$

Correct Answer:$${3\over 2}\times {1\over x}$$,$$3\over 2x$$

$$3\over 2x$$

Q4.
The solution to the equation $${6\over a}=2$$ is when $$a = $$ .
Correct Answer: 3
Q5.
Which of these is the solution to the equation $${4\over 5a}+2 = 8$$?
$$3\over 10$$
Correct answer: $$2\over 15$$
$$2\over 25$$
$$15\over 2$$
$$25\over 2$$
Q6.
Which of these is the solution to the equation $$\frac{20}{a+3}=6$$?
$$-{27\over 10}$$
$$-{3\over 10}$$
Correct answer: $$1\over 3$$
$$17\over 6$$
$$20\over 3$$