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Find 4 + 7 + 10 + 13 + 16 + . . . up to 20 terms

Option: 1

650


Option: 2

225


Option: 3

275


Option: 4

115


Answers (1)

best_answer

a = 4

d = 7 – 4 = 3

Sum of first 20 terms,

S20=n/2[2a+(n−1)d]=20/2[(2×4)+(20−1)3]

=10[8+(19×3)]=10[8+57]=650

 

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Gunjita

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