Question

rezolvati fractia 5pe21-3pe14+2pe7

Answer 1

I . calculam numitorul comun ...
     21 = 3*7
     14 = 2*7
   -----------------
c.m.m.m.c.=2*3*7 = 42;
II. $\frac{^{2)}5}{21}\,-\,\frac{^{3)}3}{14}+\frac{^{6)}2}{7}=\frac{10-9+12}{42}=\frac{13}{42}.$