Substituting particular values | Maths | Quizalize & Oak National Academy

Starter quiz

Calculate $(-5)^2$

'25' ✓
Select the correct first step to evaluate $2+3\times 5^2$

$2+3=5$

$3\times 5= 15$

$5^2=25$ ✓
Evaluate ${12\times 2\over 4}-2$

'4' ✓
Starting with the first step, put these lines of working in order to show how to evaluate ${25+2\times (2+1)^2\over 10}-4$

1

⇔

${25+2\times 3^2\over 10}-4$

2

⇔

${25+2\times 9\over 10}-4$

3

⇔

${25+18\over 10}-4$

4

⇔

${43\over 10}-4$

5

⇔

$4.3-4$
In the equation $2a+1=5-3a$ , $5-3a$ is called an ______.

'expression' ✓
Match up the directed number calculation with the correct value.

$(-10)^2$

⇔

100 ✓

$-10\times 2$

⇔

-20 ✓

$-10\times -2$

⇔

20 ✓

$2-10$

⇔

-8 ✓

$2--10$

⇔

12 ✓

$-2--10$

⇔

8 ✓

To evaluate an expression for a given value of its variable we can ______ the value in place of the variable

'substitute' ✓
Match up the expressions with their value when $r=7$

$r+50$

⇔

57 ✓

$r^2$

⇔

49 ✓

$6r$

⇔

42 ✓

$r-1$

⇔

6 ✓

$2r-10$

⇔

4 ✓

$r+1\over 4$

⇔

2 ✓
For what value of $y$ does $3y$ have the same value as $y+6$ ? $y=$ ______

'3' ✓
For which values of $y$ is $y^2-3$ smaller than $y$ ?

0 ✓

2 ✓

4

-3

-1 ✓
For the values of $a, b$ and $c$ shown evaluate the expression $2ab-c$

'26' ✓
For the values of $a, b$ and $c$ shown evaluate the expression $(2a)^2-bc$

'112' ✓

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Expressions and formulae in context can be evaluated for particular values.
Changing the value of the letter changes the expression.
Exploring what values give a particular solution can help understand the expression.
Expressions may have multiple variables and we can substitute some or all of them for numbers.

Pupils may struggle with exponents especially which value to square when variables have coefficients

Reminder of priority of operations and the exponent acts on the value it is directly preceded by.

Substitution - Substitute means to put in place of another. In Algebra, substitution can be used to replace variables with values.