Question

Fie numerele rationale a, b, c, d .Utilizand factorul comun si : daca a=4 supra 9, b+c=15 supra 8 si c-d=9 supra 20, calculati a•b+2•a•c-a•d

Answer 1

 a = 4 / 9
 b + c =15 /8
c - d = 9 / 20
a×b+2×(a×c)-(a×d)=a×b + a×c + a×c - a×d=a×(b+c)+a×(c-d)=4/9×(15/8)+4/9×(9/20)=4/9[(75+18)]/40=4/9×95/40=380/360=19/15