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The sum of the first 20 terms of an arithmetic progression with first term 5 and common difference 3 is:

Competition practiceAlgebra

A570
B640
C600
D670

Step-by-Step Solution

Sₙ =

n /2 [2 a + (n - 1) d] = 20/2 [2 (5) + 19 (3)] = 10 \times (10 + 57) = 10 \times 67 = 670

.

Answer: D) 670

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