WMA11 January 2020

2. WMA11/01​​ Edexcel IAL​​ P1 January 2020, Q2​​ (Indices)

Given y = 3x, express each of the following in terms of y. Write each expression in its simplest form.​​ 

(a)​​ 33x 

(1)

(b)​​ 13x-2

(2)

(c)​​ 8192-3x

(2)

SOLUTION​​ 

a-​​ 

33x=33x

=3x3

Where​​ y = 3x, so the equation becomes

=y3

33x=y3

b-​​ 

13x-2=3-x-2

=32-x

=323x

Where​​ y = 3x, so the equation becomes

=9y

13x-2=9y 

c-​​ 

8192-3x=81 x 9-2-3x

=81 x 93x-2

=92 x 93x-2

Since basis are same, powers are added.​​ 

=92+3x-2

=93x

=323x

=3x6

Where​​ y = 3x, so the equation becomes

=y6

8192-3n=y6