Hello May some one please help on getting the answer for number 21

x = 3/2

Step-by-step explanation:

9^x = 27

Rewrite both terms as powers of 3

9 = 3^2   and 27 = 3^3

3^2^x = 3^3

We know that a^b^c = a^(b*c)

3^(2x) = 3^3

The bases are the same, so the exponents need to be the same

2x= 3

Divide by 2

2x/2 = 3/2

x = 3/2

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb