3+4.5+6.75 is a GP find an expression for Tn and hence evaluate T6 to 3sf

Don't know it

Terms are:

3 , 4.5 , 6.75...

4.5 / 3 = 1.5

6.75 / 4.5 = 1.5

This is GP with first term t = 1 and common ratio r = 1.5

The n-th term of GP:

tn = t ∙ r ⁿ ⁻ ¹

t6 = t ∙ r ⁶ ⁻ ¹ = t ∙ r ⁵ = 3 ∙ 1.5 ⁵ = 3 ∙ 7.59375 = 22.78125