Question

Va rog frumos sa ma ajutati!

X=$\frac{1}{5}+ \frac{2}{10}+ \frac{3}{15}+ \frac{4}{20}+....+ \frac{2014}{10070}+ \frac{2015}{10075}$

Y=$\frac{3}{5}+ \frac{6}{10}+ \frac{9}{15}+ \frac{12}{20}+....+ \frac{6042}{10070}+ \frac{6045}{10075}$

a). Calculati cele doua numere.
b). Aratati ca 2X+Y este numar natural.

Answer 1

simplificam cu 2,3,.....2015
x=1/5+1/5+......+1/5=2015/5=403 sunt 2015 fractii

simplificam cu 2,3,.....2015
x=3/5+3/5+......+3/5=3*2015/5=6045/5= 1209 sunt 2015 fractii
b) 2x+y= 2*403+1209=2015

mai greu era daca era 2014