Question

If a = 2 and d = 4 then find S20​

Answer 1

Step-by-step explanation:

Sn= n/2{2a+(n-1)d}

S20= 20/2{2×2+(20-1)4}

S20= 10{4+19×4}

S20= 10×(80)

S20= 800

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