Question

Answer 1

`S = 2.3 + 3.4 + 4.5 + ... + 34.35`

`=> 3S = 2.3.3 + 3.4.3 + 4.5.3 + ... + 34.35.3`

`=> 3S = 2.3.(4-1) + 3.4.(5-2) + 4.5.(6-3) + ... + 34.35.(36-33)`

`=> 3S = 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 + 4.5.6 - 3.4.5 + ... + 34.35.36 - 33.34.35`

`=> 3S = 34.35.36 - 1.2.3 = 42834`

`=> S = 14278`