Find the sum of the first on terms of
the following A.P. as asked for:
2,6, 10, 14
up to 20 terms.
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Sn = n/2 x [2a+(n-1)d]
= 20/2 × [2x2+(20-1)x4]
= 10×(4+19×4)
= 10×(4+76)
= 10x80
= 800
:-)
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