Originally Posted by

**Cezar**
Hi, I have an exercise that would be considered to belong to calculus, but i got stuck on solving a sum(even further, i have the final step at the answer, but I don't understand how they got to the conclusion).

Basically i have this sum, but i don't know the steps between where i got stuck and the last step from the answer.

Where I got stuck:

. . . . .[tex]a_1\, \sqrt{\strut a_1\,}\, +\, a_2\, \sqrt{\strut a_2\, }\, +\, ...\, +\, a_n\, \sqrt{\strut a_n\,}\, =[/tex]

Last step from the answer:

. . . . .[tex]a_1\, -\, a_2\, +\, a_2\, -\, a_3\, +\, ...\, +\, a_n\, -\, a_{n+1}\, =[/tex]

. . . . .[tex]a_1\, -\, a_n[/tex]

I wold really appreciate if someone could explain me the steps in between.

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