If a and b are two consecutive integers such that a>b and product of the two integers is c. Then (a+b)2 =
1-4c
1+4c
1-2c
1+2c
(a+b)2 = (a−b)2 + 4ab = 1 + 4c (since both are consecutive)
Sum of integers from 1 to 100 that are divisible by 2 is a, by 5 is b and by both 2 and 5 is c. Find the sum of integers which are divisible 2 or 5.