Question

1 supra 1ori2+1 supra 2ori3+1 supra 4ori5

Answer 1

1/1·2 + 1/2·3 +1/3·4 + 1/4·5 = 1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 =
1/1 - 1/5 = 4/5

Answer 2

"1 supra 1ori2+1 supra 2ori3+1 supra 4ori5 "

1/(1·2) +1/(2·3) +1/(4·5)

[tex]\it \dfrac{1}{1\cdot2} +\dfrac{1}{2\cdot3} +\dfrac{1}{4\cdot5} = \dfrac{^{30)}1}{\ \ 2}+\dfrac{^{10)}1}{\ 6} +\dfrac{^{3)}1}{\ 20} =\dfrac{30+10+3}{60} = \\\;\\ = \dfrac{\it43}{\it60}. [/tex]