Question

Without adding find the sum 1 +3+5+7+.........................+47+49

Answer 1

Answer:

We see that the series forms an A.P. with first term(a)=1 and common difference(d)=2.

Therefore, by using the formula

Sn(Sum of n terms)=n/2[ 2a +(n-1)d]

S25(Sum of 25terms)=25/2[2(1)+(25-1)2]

                                  = 25/2[2+48]

                                   25*25=625 Ans.

Step-by-step explanation:

Answer 2

625

Step-by-step explanation:

sum of first n odd naturals is n²