Question

Find the following sums .

a) 1 + 2 + 3 + 4 + 5 + . . . . . . . . + 20

b) 8 + 16 + 24 + 32 + 40 + . . . . . . . . + 160

c) 5 + 13 + 21 + 29 + 37 + . . . . . . . + 157​

Answer 1

Answer:

a) a=1 , d=2-1=1 , n = 20

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

Sn=20/2[2×1+(20-1)1]

Sn=10(2+19)

Sn=10(21)

Sn=210

Step-by-step explanation:

through this process u can do the rest of the parts

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