Question

What is the sum of an odd numbers between 1 to 50.​

Answer 1

Answer:

625

Step-by-step explanation:

1+3+5+7+9=25

than means 11+13+15+17+19 = once side will be 25 and tens side will be 5 in addition we have to take only once side 9f the sum i.e. 2+5=7 ans =5

same

21+23+25+27+29+=125

31+33+35+37+39=175

41+43+45+47+49=225

25+75+125+175+225=625

Answer 2

Answer:

625

Step-by-step explanation:

The odd numbers between 1 & 50 are

1, 3, 5, 7, .... , 49.

here t1 = a = 1, t2 = 3, tn = 49

d = t2 -t1 = 3 - 1 = 2.

:. tn = a + (n - 1) d

:. 49 = 1 + (n - 1) 2

:. 49 = 1 + 2n - 2

:. 49 = 2n - 1

:. 49 + 1 = 2n

:. 2n = 50

:. n = 50 / 2

:. n = 25

:. Sn = n / 2 [ 2a + (n + 1) d ]

:. S25 = 25 / 2 [ 2(1) + ( 25 - 1) 2 ]

          = 25 / 2 [ 2 + 48 ]

          = 25 / 2 [ 50 ]

          = 25 [ 25 ]

:. S25  = 625