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1. a & b invers proportional cu 5 & 8 . a+b=26 a=? b=?
2. a&b invers proportional cu 2 si 3. 6a+9b=36 . a=? b=?


Răspuns :

1
a=k/5
b=k/8
a+b=26
k/5+k/8=26
8k+5k=1040
13k=1040
k=80
a=80/5=16
b=80/8=10

2
a=k/2
b=k/3
6a+9b=36
6* k/2+9*k/3=36
3k+3k=36
6k=36
k=6
a=6/2=3
b=6/3=2

3
a=k/2
b=k/3
c=k/4
6a+9b-4c=75
6* k/2+9*k/3 -4 *k/4=75
3k+3k-k=75
5k=75
k=15
a=15/2=7,5
b=15/3=5
c=15/4=3,75