Substitution scenarios
1.
If x = 5, evaluate ...
a.
b.
c.
d.
e.
2.
3x
x+4
6–x
x
/5
½(x + 15)
If x = 3, evaluate ...
a.
b.
c.
d.
e.
x2
27
/x
15 – 2x
2x + 3
2(x + 1.5)
3.
Create five expressions equal to 9, if x = 2. (e.g. 4x + 1)
4.
Below are the prices of some items in a supermarket:
water
w = 80p
pack of cola
c = £3.30
pizza
p = £2.70
a.
b.
c.
d.
Calculate the cost of:
5.
melon
m = £2.10
3w
c+p
2m + c
w+c+p+m
a
The area of this piece of paper is given as:
ab = 24 (a and b are both integers).
b
Find eight possible sets of values for a and b.
6.
Here are 4 expressions:
x2
x+1
x3
1
/x
a. x = 2
b. x = -2
c. x = ½
Arrange them into ascending
order if ...
Extension task
If a = 1, b = 2, c = 3 ... z = 26, find words whose letter sum is ...
a. 27
© www.teachitmaths.co.uk 2012
b. 24
16631
c. 60
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Substitution scenarios
Answers
1.
a.
b.
c.
d.
e.
3.
4.
2.
3x = 15
x+4=9
6–x=1
x/5 = 1
½(x + 15) = 10
Examples:
x+7
5x – 1
x2 + 5
2x + 5
6x – 3
x3 + 1
a.
b.
c.
d.
3w = £2.40
c + p = £6.00
2m + c = £7.50
w + c + p + m = £8.90
a
a
a
a
1, b = 24
3, b = 8
6, b = 4
12, b = 2
a.
b.
c.
d.
e.
x2 = 9
27
/x = 9
15 – 2x = 9
2x + 3 = 9
2(x + 1.5) = 9
3x + 3
7x – 5
5.
6.
=
=
=
=
a=
a=
a=
a=
2, b = 12
4, b = 6
8, b = 3
24, b = 1
1
/x
x3
x3
If x = 2:
If x = -2
If x = ½
x+1
x+1
x2
x2
1
/x
x+1
x3
x2
1
/x
Extension task
If a = 1, b = 2, c = 3 ... z = 26, find words whose letter sum is ...
a. 27
b. 24
c. 60
e.g. ball
e.g. cat
e.g. teacher
© www.teachitmaths.co.uk 2012
16631
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