Question

show the steps for the answers ​

Answer 1

Answer:

The sum of first twenty terms of arithmetic series is 990

Step-by-step explanation:

a=2

d=7-2=5

n=20

Sn=n/2[2a+(n-1)d]

=20/2[2×2+(20-1)5]

=10[4+19(5)]

=10(4+95)

=10×99

=990

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