Question

the sum of first 2 even natural number is given by the relation S=n(n+1).find n if the sum Sum is 420

Answer 1

420 = n (n + 1 )      use distributive property

400 + 20 = n2 + n     transpose

400 - n2 = n - 20     get the square root of 400 - n2 then it becomes

20 - n = n - 20        transpose

20 + 20 = n + n       then add

40 = 2n         then divide by 2 on each side to get the value of n

n = 20

Answer 2

hope you satisfied with the answer