Question

find in terms of k the sum of all the odd integers lying btwn 2k and 4k

Answer 1

We have that the number of terms is (4k-2k)/2 =k, the first term is 2k +1 and last term 4k-1 so using the formula S = n/2 (a_1 +a_n)

S = k/2 (2k +1 + 4k -1) = k/2(6k) = 3k^2.

Answer 2

how did you get the number of terms part?

Answer 3

Well, take any 2 actual numbers of form 2k, say 40 and 36, the number of numbers after 36 is 4 but we only want half of them so 40-36/2

Answer 4

i dont understand.......=(

Answer 5

There's two kinds of integers, odd and even and they alternate.

Answer 6

Is it something else u don't understand?