Răspuns:
Explicație pas cu pas:
Se numeste suma telescopica:
faci la a) de exemplu:
[tex](\frac{1}{1X2} +\frac{1}{2X3} +\frac{1}{3X4} +...+\frac{1}{50X51} ) = (\frac{1}{1X2}+ \frac{3-2}{2X3} + \frac{4-3}{3X4}+...+\frac{51-50}{50X51}) = (\frac{1}{1X2} + \frac{3}{2X3}-\frac{2}{2X3}+\frac{4}{3X4}- \frac{3}{3X4}+...+\frac{51}{50X51}-\frac{50}{50X51})=(\frac{1}{2} +\frac{1}{2}- \frac{1}{3} +\frac{1}{3} -\frac{1}{4} +...+\frac{1}{50}-\frac{1}{51} )=(\frac{1}{1} -\frac{1}{51}) amplific.pe \frac{1}{1} .cu 51 =>(\frac{51}{51}-\frac{1}{51})=\frac{50}{51}[/tex]
Sper ca te-am ajutat ;)
