Question

repedee cat mai multe exercitii​

Answer 1

9. 2x+5y-z=105

x/3=y/4=z/5

x=3k

y=4k

z=5k

2×3k+5×4k-5k=105

6k+20k-5k=105

26k-5k=105

21k=105

k=105:21

k=5

x=3×5

x=15

y=4×5

y=20

z=5×5

z=25

E=3x+2y+z

E=3×15+2×20+25

E=45+40+25

E=110

12. P=120cm

2(L+l)=120cm

L+l=120cm:2

L+l=60cm

l/5=L/7

l=5k

L=7k

7k+5k=60cm

12k=60cm

k=60cm:12

k=5cm

l=5×5cm

l=25cm

L=7×5cm

L=35cm