What is the sum of the series? 20∑ t=1 4-3t

Answer 1

The formula for sum of an arithmetic series is S_n=n/2(a₁+a_n)

n=20

a₁=4-3(1)=1

a₂₀=4-3(20)=-56

Sn=n/2(a1+an)

S₂₀=20/2(1+-56)

S₂₀=10(-55)

S₂₀=-550