Question

find the sum of the first 30 terms of the equation below: an=4n+1

Answer 1

Let n = 30

We are actually looking for a_30.

a_30 = 4(30) + 1

a_30 = 120 + 1

a_30 = 121

Answer 2

Answer:

1,890 is the sum of the first 30 terms of the equation .

Step-by-step explanation:

$a_n=4n+1$

if , n = 1

$a_1=4\times 1+1=5$

If, n = 2

$a_2=4\times 2+1=9$

If, n = 3

$a_3=4\times 3+1=13$

The arithmetic sequence comes out to be:

5, 9, 13........

a = 5

d = $a_2=a_1=9-5=4$

The sum of first 30 terms is given by:

$S_n=\frac{n}{2}\times (2a+(n-1)d)$

$S_{30}=\frac{30}{2}\times (2\times 5+(30-1)\times 4)$

$S_{30}=1,890$

1,890 is the sum of the first 30 terms of the equation .