Question

Find the sum of the first 50 terms of the arithmetic sequence with the first term 3 and the third term 11.

Answer 1

Answer:

3,7,11,15,19,23,27,31,35,39,43,47,51,55,59,63,67,71,75,79,83,87,91,95,99,103,107,111,115,119,123,127,131,143,147,151,155,159,163,167,171,175,179,183,187,191 and 199

all u do is add 4 each time as you can see.

There is thr first 50

hoped that helped:P

Answer 2

Answer:

$S_{50}$ = 5050

Step-by-step explanation:

The sum to n terms of an arithmetic sequence is

$S_{n}$ = $\frac{n}{2}$ [ 2a₁ + (n - 1)d ]

where a₁ is the first term and d the common difference

The nth term of an arithmetic sequence is

$a_{n}$ = a₁ + (n - 1)d

Here a₁ = 3 and a₃ = 11 , then

3 + 2d = 11 ( subtract 3 from both sides )

2d = 8 ( divide both sides by 2 )

d = 4

Then

$S_{50}$ = $\frac{50}{2}$ [ (2 × 3) + (49 × 4) ]

      = 25(6 + 196)

      = 25 × 202

      = 5050