Question

Find the Sum of odd integers from 1 to 2001.

Answer 1

its answer is 1002001
firstly we will find (n) from the A.P
l=a+(n-1)d
and then putting the value of (n) in the formula
s(n)=n/2{2a+(n-1)d}

Answer 2

Answer:

1,002,001

Step-by-step explanation:

Solution:

To find su of all odd integers from 1 to 2001

we can convert it into an A.P.

thus it can be represted as

1,3,5,7,9,...,2001

To find the sum: calculate n first

a = 1

d= 2

2001 = a+(n-1)d

2001 = 1+(n-1)2

2000=(n-1)2

n-1 =1000

n=1001

Sn= $\frac{n}{2}[2a+(n-1)d]$

 =$\frac{1001}{2} [2+(1001-1)2]\\ \\ \\= \frac{1001}{2} [2002]\\ \\ \\ =1001(1001)\\ \\ \\ =1,002,001$