Changing the subject

Grade C

Example 1

a = 4b, Make b the subject of the formulae:

Lets see how we got the a. . . in a=4b

Do the exact opposite to get b . . .

We get a

Start with b

Multiply by 4x4

We get b

Divide by 4÷4

Start with a

So, b = a÷8 or b = a8

Example 2h= 8e + 2, Make e the subject of the formulae:

Lets see how we got the h. . . in h=8e + 2

Do the exact opposite to get e . . .

We get h

Start with e

Multiply by 8x8

Add 2+2

We get e

Divide by 8÷8

Subtract 2-2

Start with h

So e=(h-2)÷8 or e= (h-2) 8

Example 3b= 3d + 11, Make d the subject of the formulae:

Lets see how we got the b. . . in b=3d + 11

Do the exact opposite to get d . . .

We get b

Start with d

Multiply by 3x3

Add 11+11

We get d

Divide by 3÷3

Subtract 11-11

Start with b

So d=(b-11)÷3 or d= (b-11) 3

Example 4v= 7(c + 9), Make c the subject of the formulae:

Lets see how we got the v. . . in v=7(c + 9)

Do the exact opposite to get c . . .

We get v

Start with c

Add 9+9

Multiply by 7x7

We get c

Subtract 9-9

Divide by 7÷7

Start with v

So c=(v÷7) -9 or c= v - 9 7

Questions 1

Change of SubjectMake the indicated variable given in brackets the subject of each formula:

)( )( bba 21

)( )( tatuV 2

)( )( )( ssnm 53

)( )( )( akba 234 2

Questions 1

Change of Subject - answers

)( )( bba 21 2ab

)( )( tatuV 2auV

t

)( )( )( ssnm 535

5nms

n

msor

5

)( )( )( akba 234 2 3

32 bka

b

kaor

3

2