Question

Observe the following pattern

1 = 1/2 (1×(1+1))

1+2 = 1/2 (2×(2+1))

1+2+3 = 1/2 (3×(3+1))

1+2+3+4 = 1/2 (4×(4+1))

And find the values of .

(i) 31+32+….+50

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Answer 1

Answer:

810 is the answer of this question by the formula of AP

Answer 2

Step-by-step explanation:

Her

From the observation we conclude

sum of consecutive natural number starting from 1 = n(n+1)/2

here

31+32+....+50= 50(51)/2-30(31)/2

= 25(51)-15(31)

= (20+5)(51)-(10+5)31

= (1020+255)-(310+155)

= 1275-465

= 810

hope it helps ✌