Find the 20th term of the arithmetic sequence in which a1= 3 and d = 7 ?

Question

a 143

b 136

c 140

d 133

Answer 1

an = a1 + (n-1)d

a20 = 3 + (20-1)(7)

a20= 3 + 19 x 7

a20 = 3 + 133

a20 = 136

Therefore the answer is B.

Answer 2

i would go with B

1 simple my answer

Arithmetic sequence has the 1st term and the common like different thing's.

so going with the a+d[n-1]...........

then i would say this***** [a=3, d=7] and then [n = 20]

then the 20th term is equal then

so then you can go with [3+7],[20-1]=3+7

then go through this

19=3+133=136

that's why the answer is [B]



  

Answer 3

If an arithmetic sequence has first term a and common difference d, then the nth term of the sequence is equal to a + d*(n - 1).  In this case, a = 3, d = 7, and n = 20, so the 20th term is equal to:

3 + 7*(20 - 1) = 3 + 7*19 = 3 + 133 = 136

So the answer is B.