Question

23) Fie numerele rationale  a , b ,c ,d

a. Daca a*b=2 supra 15 si a*c = 11 supra 75, calculate a*(b+c)

b. Daca a * c = 7 supra 36 si b* c =19 supra 48 , calculate c*(b-a)

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

b.
a*c = 7/36
b*c =19/48
c*(b-a)=c*b-c*a=19/48-7*36=57/144-28/144=28/144

c. a=5 / 6
 b + c =7 /20
c-d=1 / 24
a*b+2*a*c-a*d=a*b+a*c+a*c-a*d=a*(b+c)+a*(c-d)=5/6*7/20+5/6*1/24=
=1/6*7/4+5/6*1/24=1/6*42/24+5/6*1/24=6/144+5/144=11/144