Question

1. Aflati trei numere naturale a,b,c care verifica simultan , egalitatiile:
a+b=80
a+c=90
b+c=100
2. Sa se stie ca ab+ac+a=180 si b+c 17 . Aflati a .

Answer 1

a+b=80
a+c=90
b+c=100
2a+2b+2c=80+90+100
2(a+b+c)=270
a+b+c=270:2
a+b+c=135
135-80=55(b)
135-90=45(c)
135-100=35(a)
2)ab+ac+a=180
b+c=17 b=17-a
2a(b+c)+a=180
2ax17+a=180
35a=180
a=180:35
a=6
b=17-6=11
66+6c+6=180
72+6c=180
6c=180-72
6c=108
c=108:6=18