Răspuns :
a+b+c=3,5⇔a=2b si b-0,5=c⇔2b+0,5 *b+b=3,5⇔3,5*b=3,5⇔b=1
a=2*1⇔a=2
c=1-0,5⇔c=0,5
a=2*1⇔a=2
c=1-0,5⇔c=0,5
a)
A+B+C=3.5
A=2B
B-0.5=C
=> 2B+B+B-0.5=3.5
4B=4
B=1
A=2
C=0.5
b)
A+B+C=1.7
A=C-1/2
C+2/5=B
C-1/2+C+2/5+C=1.7
3C=17/10+1/2-2/5=17/10+5/10-4/10=18/10=1.8
C=1.8:3
C=0.6
A=0.6-1/2=0.6-0.5=0.1
B=0.6+2/5=6/10+2/5=3/5+2/5=5/5=1
c)A+B+C=20
4A=B
3A=C
A+4A+3A=20
8A=20
A=20/8=5/2=2.5
B=10
C=7.5
A+B+C=3.5
A=2B
B-0.5=C
=> 2B+B+B-0.5=3.5
4B=4
B=1
A=2
C=0.5
b)
A+B+C=1.7
A=C-1/2
C+2/5=B
C-1/2+C+2/5+C=1.7
3C=17/10+1/2-2/5=17/10+5/10-4/10=18/10=1.8
C=1.8:3
C=0.6
A=0.6-1/2=0.6-0.5=0.1
B=0.6+2/5=6/10+2/5=3/5+2/5=5/5=1
c)A+B+C=20
4A=B
3A=C
A+4A+3A=20
8A=20
A=20/8=5/2=2.5
B=10
C=7.5