Question

40 +41 +42 + ........ + 60 = ? with formula used​

Answer 1

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Answer 2

Answer:

A first term= 40

D. common difference = +1

L last term = 60

now An= a+ (n-1)d

60 = 40 + (n - 1) 1

60 -40 = n-1

20 = n-1

21 = n

now Sn = n/2 × ( a + l)

= 21/2 × ( 40 + 60 )

= 21 /2 × 100

21 × 50

1050.

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