Question

11th math kc sinha exercise 17.3​

Answer 1

Answer:

Step-by-step explanation:

(9.) .Find the sum of all integers from 1 to 100 which are multiples of 2 or 5

Solution:-

Multiple of 2

a=2. d=2. Tn=100

Tn=a+(n-1)d

100=2+(n-1)2

100=2+2n-2

100=2n

n=100/2

n=50

Multiple of 5

a=5. d=5. Tn=100

Tn=a+(n-1)d

100=5+(n-1)5

100=5+5n-5

n=100/5

n=20

Multiple of 2 and 5

a=10. d=10. Tn=100

100=10+(n-1)10

100=10+10n-10

100=10n

n=100/10

n=10

Sn=n/2(a+tn)

= 10/2(10+100)

=5(110)

Sn=550

Sum of all integers from 1 to 100

=2550+1050-550

=3050 ans