Question

Find the sum of numbers 3,7,11, .... Upto 40 terms

Answer 1

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Answer 2

Answer:

Step-by-step explanation:

first term (a) = 3

Common difference (d) = 7-3 = 4

Number of terms(n) = 10

aSum = n/2[2a + (n-1)d]

Subsitute the values

aSum = 10/2[2x3 + (10-1)4]

= 5(6 + 36)

= 5x42

= 210