Question

Q.1)Find the sum of first 15 multiples of 8.
Q.2)Find the sum of the odd numbers between 0 and 50.

No spam
Irrelevant answers will be reported on spot​

Answer 1

Step-by-step explanation:

1.ans. Let to be a is the first term and ‘d’ is the common difference and l is the last term of Given Arithmetic Sequence or Progression.

Arithmetic Sequence or Progression;- 8,16,24,32….

Here, the First term = 8

Common Difference = 8

Number of terms = 15

We know that Formula of Summation of Arithmetic Sequence or Progression.

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

S15 = 15/2(2×8+(15-1)8

= 15/2(16+(14)8)

= 15/2(16+112)

= 15/2 x 128

= 15 x 64

= 960

The sum of the first 15 multiples of 8 is 960.

2.ans. The odd numbers between 0 and 50 are 1,3,5,7,9…49

Therefore, it can be observed that these odd numbers are in an A.P.

a=1,d=2,l=49

l=a+(n−1)d

49=1+(n−1)2

48=2(n−1)

n−1=24

n=25

Sn=2n(a+l)

S25=225(1+49)

=225×50=625

Answer 2

$\large \sf \red{\{{Answer :}\}}$

Ans1. Sum of first 15 multiples of 8 are 960.

Ans2. Sum of the odd numbers between 0 and 50 is 625.