Question

The value of-1+2-3+4-5+6...-39+40 is equal to

Answer 1

We have :-

=> - 1 + 2 - 3 + 4 - 5 + 6 ..... - 39 + 40

=> - 1 + (2 - 3) + (4 - 5) + ..... + (38 - 39) + 40

=> - 1 - 1 - 1 - ..... - 1 + 40

=> - 20 + 40 = 20

One more method :-

=> (- 1 - 3 - ..... - 39) + (2 + 4 + ..... + 40)

=> - 400 + 420 = 20

Hope it'll help you.....

Answer 2

Answer:

that is correct

Step-by-step explanation:

you can Mark