Question

Given a+b=7 and a–b=3, find:
3^a÷3^b

Answer 1

27

Explanation:

a + b = 7 ....eq 1

a - b = 3 ....eq 2

solve simultaneously using elimination method

add eq 2 to eq 1

a + b = 7

+

a - b = 3

2a = 10

a = 5

substitute the value of a in eq 1

5 + b = 7

subtract 5 from both sides

5 - 5 + b = 7- 5

b = 2

Now, slot in the values of both a and b

3^a÷3^b

we will solve using PEDMAS

3^5 / 3^2

`3^(5-2)`

`3^(3)`

27