Question

what is the value of 0-1+2-3+4-5+6-7 ................. +16-17+18 -19+20

Answer 1

Answer:

10

Step-by-step explanation:

= -(+1+3+5+7+9+11+13+15+17+19)+(2+4+6+8+10+12+14+16+18+20)

=- 100+110

=   10

Answer 2

Given ; 0-1+2-3+4-5+6-7 ................. +16-17+18 -19+20

To Find ; the value

Solution ; 0-1+2-3+4-5+6-7 ................. +16-17+18 -19+20

This problem can be solved using ap

Two arithmetic progression one of positive and one negative

0+2+4 ......-(1+3+5+7...)

Solving first AP 0  +2 +4 +..... 20

a=0 n= 11 d =2

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

= 11(20)/2

=110

Solving second Ap

a = 1 d = 2 n=10

sn = 10(2+18)/2

=100

Hence the sum is 110 -100 that is 10