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1)Calculati:
a)[tex] \frac{3!+4!+5!}{2!+3!+5!} [/tex]
b)[tex] \frac{n!}{(n-3)!} [/tex]
c)[tex] \frac{10!-9!}{11!-10!} [/tex]
d)[tex] \frac{1}{2!}+ \frac{2}{3!} + \frac{3}{4!} [/tex]


Răspuns :

a) [tex] \frac{1*2*3+1*2*3*4+1*2*3*4*5}{1*2+1*2*3+1*2*3*4*5} = \frac{6+24+120}{2+6+120} = \frac{150}{128} [/tex]
b) - nu stiu
c) [tex] \frac{1*2*3*4*5*6*7*8*9*10 - 1*2*3*4*5*6*7*8*9}{1*2*3*4*5*6*7*8*9*10*11- 1*2*3*4*5*6*7*8*9*10} = \frac{3.628.800-362.880}{39.916.800 - 3.628.800} = [/tex][tex] \frac{3.265.920}{36.288.000} [/tex]
d) [tex] \frac{1}{1*2} + \frac{2}{1*2*3} + \frac{3}{1*2*3*4} = \frac{1}{2} + \frac{2}{6} + \frac{3}{24} = \frac{12}{24} + \frac{8}{24} + \frac{3}{24} = \frac{23}{24} [/tex]
Exercitiul d l-am amplificat, prima fractie cu 12 iar a doua cu 4 ca sa am factor comun pe 24.