1. p = 6 x = ½ a = 4 Starter – Solve: 2p + 9 = 21 4x – 2 = 8 – 16x
3(a + 2) = 26 – 2a

2. Step-by-Step Guide Firstly decide what needs to be on its own.
Secondly move all terms that contain that letter to one side. Remember to move all terms if it appears in more than one.
Thirdly separate out the required letter on its own.

3. Rearrange the formula to make a the subject:
v = u + at
v - u = at
v - u = a t

4. Rearrange the formula to make p the subject:
pk + q = h
pk = h - q
p = h – q k

5. VR
V = IR
I = ? V R
Amber R V

6. Vπr²
V = πr²h
h = ? V
πr²
Amber
Vr² π

7. a(v – u)
v = u + at
t = ?
v + u a
Amber
v - u a

8. A 2h
A = ½bh
b = ? 2A h
Amber
2Ah

9. 2A - b h
A = ½(a + b)h
a = ?
2Ah b
Amber
2A – b h

10. c - a
a² + b² = c²
b = ?
√(c² - a²)
Amber
√(a² - c²)

11. Cut out the cards ONE AT A TIME.
Match up the pairs of formulae where c or d is the subject.
Show ALL your working in your book.

12. Answers

13. Rearrange the formula to make g the subject:
g = p + gf
g - gf = p
g(1 – f) = p
g = p_
1 - f

14. Rearrange the formula to make a the subject:
a = u + at
a - at = u
a(1 – t) = u
a = u_
1 - t

15. Rearrange the formula to make n the subject:
m(x² + n) = n(t² – s)
mx² + mn = nt² - ns
mx² = nt² - ns - mn
mx² = n( t² – s - m)
mx²__ = n
t² - s - m

16. Rearrange the formula to make x the subject:
m = p – n x
m + n = p x
x(m + n) = p
x = p_
m + n
Mention that the answer could be displayed differently if the LHS were chosen for x

17. Rearrange the formula to make n the subject:
m(x + n²) =n²
mx + mn² = n²
mx = n² - mn²
mx = n²( 1 – m)
mx = n²
1-m √
( )
mx = n
1 - m
Mention that the answer could be displayed differently if the LHS were chosen for n
We require n not n²

18. Answers

19. Swap books and rearrange.
Plenary
Write a formula in your books for your partner to change the subject of.
Swap books and rearrange.