Răspuns:
a=12
b=24
c=48
Explicație pas cu pas:
a+b+c=84
a+a*q+a*q^2=84
a*(1+q+q^2)=84 (1)
a=x1
b=x1+3r
c=x1+9r
a+b+c=84
x1+x1+3r+x1+9r=84
3x1+12r=84
3*(x1+4r)=3*28
impart la 3
x1+4r=28
x1=28-4r
x1=4*(7-r)
a=x1=4*(7-r)
inlocuiesc in relatia (1)
4*(7-r)*(1+q+q^2)=84
impart la 4
(7-r)(1+q+q^2)=21
(7-r)(1+q+q^2)=3*7
7-r=3
r=4
1+q+q^2=7
q+q^1=7-1=6
q*(1+q)=2*3
deci q=2
a=4*(7-r)=4*(7-4)=4*3=12
b=12*q=12*2=24
c=12*2^2=12*4=48
verificare 12+24+48=84
#copaceibrainly
