Question

11 + 12 + 13 + 14 + 15 + ...50
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Answer 1

Answer:

115

Step-by-step explanation:

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Answer 2

Answer:

The required answer is 1220.

Step-by-step explanation:

The each term is obtained by adding 1 to the previous term. Hence, the sequence is Arithmetic Progression (A.P)

• first term, a = 11

• common difference, d = 1

First, let's find which term is 50.

nth term of an A.P is given by,

 $\longmapsto \sf a_n=a+(n-1)d$

aₙ = 11 + (n - 1)(1)

50 = 11 + n - 1

50 = 10 + n

 n = 50 - 10

 n = 40

∴ 40th term is 50.

We have to find the sum of first 40 terms in the given A.P

Sum of first n terms in A.P. is given by,

 $\longmapsto \sf S_n=\dfrac{n}{2}[2a+(n-1)d]$

$\rm S_{40}=\dfrac{40}{2}[2(11)+(40-1)(1)] \\\\ \rm S_{40}=20[22+39] \\\\ \rm S_{40}=20(61) \\\\ \rm S_{40}=1220$

Therefore, the required answer is 1220.