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 =5 supra 6,b+c= 7 supra 20 si c-d= 1 supra 24,calculati a*b+2*a *c-a*d

Answer 1

a*b=2/15
a*c= 11/75
 a*(b+c) =a*b+a*c=2/15+11/75=(10+11)/75=21/75=7/25

a =5/6
b+c= 7/20
c-d= 1/24
 a*b+2*a *c-a*d =a(b+2c-b)=a(b+c+c-d)=5/6(7/20+1/24) =5/6(42+5)/120 =5/6*47/120=47/144