2. Example 1
a = 4b, Make b the subject of the formulae:
Lets see how we got the a. . . in a=4b
Start with Multiply by 4 We get
b x4 a
Do the exact opposite to get b . . .
We get Divide by 4 Start with
b 4 a
So, b = a 8 or b = a
8
3. Example 2
h= 8e + 2, Make e the subject of the formulae:
Lets see how we got the h. . . in h=8e + 2
Start with Multiply by 8 Add 2 We get
e x8 +2 h
Do the exact opposite to get e . . .
We get Divide by 8 Subtract 2 Start with
e 8 -2 h
So e=(h-2) 8 or e= (h-2)
8
4. Example 3
b= 3d + 11, Make d the subject of the formulae:
Lets see how we got the b. . . in b=3d + 11
Start with Multiply by 3 Add 11 We get
d x3 +11 b
Do the exact opposite to get d . . .
We get Divide by 3 Subtract 11 Start with
d 3 -11 b
So d=(b-11) 3 or d= (b-11)
3
5. Example 4
v= 7(c + 9), Make c the subject of the formulae:
Lets see how we got the v. . . in v=7(c + 9)
Start with Add 9 Multiply by 7 We get
c +9 x7 v
Do the exact opposite to get c . . .
We get Subtract 9 Divide by 7 Start with
c -9 7 v
So c=(v 7) -9 or c= v - 9
7
6. Change of Subject
Make the indicated variable given in brackets the subject of each
formula:
(1) a b 2 (b )
(2)V u at (t )
(3) m 5(n s ) (s )
(4) 3(a 2 b) 2k (a )
Questions 1
7. Change of Subject - answers
(1) a b 2 (b ) b a 2
V u
(2)V u at (t ) t
a
m 5n m
(3) m 5(n s ) (s ) s or s n
5 5
2k 3b 2k
(4) 3(a 2
b) 2k (a ) a or a b
3 3
Questions 1
