Question 33874: Use the arithmetic sequence of numbers 1, 3, 5, 7, 9,…to find the following:
a)What is d, the difference between any 2 terms?
b)Using the formula for the nth term of an arithmetic sequence, what is 101st term?
c)Using the formula for the sum of an arithmetic series, what is the sum of the first 20 terms?
Answer by sarah_adam(201)   (Show Source):
You can put this solution on YOUR website! Use the arithmetic sequence of numbers 1, 3, 5, 7, 9,…to find the following:
a)What is d, the difference between any 2 terms?
d = 3 - 1 = 2
b)Using the formula for the nth term of an arithmetic sequence, what is 101st term?
a = 1 ;d = 2
Tn = a+(n-1)d
T 101 = 1+(101 - 1)*2
T 101 = 1+100*2 = 201
c)Using the formula for the sum of an arithmetic series, what is the sum of the first 20 terms?
Sum of n terms in an A.P is Sn = n/2*{2*a+(n-1)*d}
Here n = 20 ; a =1 ; d = 2
S 20 = 20/2*{2*1+(20-1)*2}
S 20 = 10*{2+38}
S 20 = 10*40 = 400
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