Answer:

20 475

Step-by-step explanation:

Sn = a1(1-r^n)/1-r

s12 = 5(1-2^12)/1-2

      = 5(1-4096)/-1

      = 5(-4095)/-1

      = -20 475/-1

      = 20 475

thank me later :>

Answer:

230

Step-by-step explanation:

Before we find the sum of the first 10 terms of the arithmetic sequence {5, 9, 12, 17, ...}, let's find first the common difference and the 10th term of the sequence.

d = a_{2}- a_{1}a

2

−a

1

= 9-5 = 49−5=4

Use the formula:

\begin{gathered}a_{n} =a_{1} (n-1)d\\\\a_{10} =5+ (10-1)4\\a_{10} =5 +(9)4\\a_{10} =5+ 36\\a_{10} =41\\\end{gathered}

a

n

=a

1

(n−1)d

a

10

=5+(10−1)4

a

10

=5+(9)4

a

10

=5+36

a

10

=41

I prefer this formula to find the su