use the backward substitution method to obtain the closed form formula for the recurrence relation

an= 2an-1 + 1, and a0 =0.

Step-by-step explanation:

So, we can infer that

and we only need to find out a formula for this sum (a geometric reason with common ratio 2)

Let's call

then,

hence,

and we have our closed formula for the sequence

hi,

6x times 4 is 24x and 5 times 4 is 20, so the answer is 24x+20.

hope this and for a little humor i am groot.

addition

step-by-step explanation: