Question

clasa a 7 a
sem 2
coroana​

Answer 1

Răspuns:

a) $\left \{ {{4x+y=10} \atop {x-6y=15}} \right.$

x=15+6y

4(15+6y)+y=10

60+24y+y=10

25y=-50 /:25 ⇒ y=-2

x=15-2·6  ⇒ x=3  

b) $\left \{ {{\frac{x+1}{2}+\frac{x-y}{3} =3} /*6\atop {\frac{x-y+5}{2} =2y+4} /*2\right.$

$\left \{ {{3x+3+2x-2y=18} \atop {x-y+5=4y+8}} \right.$

$\left \{ {{5x-2y=15} \atop {x-5y=3}} \right.$

x=3+5y

15+25y-2y=15

23y=0 ⇒ y=0, x=3

Explicație pas cu pas: