Question

Fie numerele rationale a,b,c,d.
  a) Daca a*b= 2 supra 15 si a*c= 11 supra 75, calculati a*(b+c);
  b) Daca a*c= 7 supra 36 si b*c= 19 supra 48, calculati c*(b - a).
  c) Daca a=5 supa 6, b+c= 7 siupra 20 si c-d=1 supra 24, calculati a*b+2*a*c-a*d,

Answer 1

1) a*(b+c)= a*b +a*c = 2/15 + 11/75= (14+11)/75= 25/75= 1/3

2)c* (b-a) = bc - ac= 19/48 - 7/36= (57-28)/144= 29/144

3)ab + 2ac -ad= ab +ac+ac -ad= a(b+c)+a(c-d)=

= 5/6 * 7/20 + 5/6 * 1/24= 7/24 + 5/ 144=   (42+5)/144= 47/144