Question

Rezolvati prin metoda substitutiei sistemele:
b)4x-2y=0
x-y=-1
f)x-2y=-8
3x+4y=-4

Answer 1

Răspuns:

b)X=1/3

Y=-2/3

f)x=-4

Y=6

Explicație pas cu pas:

B)4x-2y=0

X-y=-1 |x2

4x-2y=0

2x-2y=-2

(adunam)

6x=-2

X=-2/6

X=1/3

1/3-y=-1

Y=-2/3

F)x-2y=-8 |x2

2x-4y=-16

2x-4y=-16

3x+4y=-4

Adunam

5x=-20

X=-20/5

X=-4

4-2y=-8

2y=12

Y=6

Sper ca te-am ajutat!

Answer 2

$\it f)\ \ \begin{cases} \it x-2y=-8\ \Rightarrow\ x=2y-8\ \ \ \ \ (*)\ \ rela\c{\it t}ia\ de\ substitu\c{\it t}ie\\ \\ \it 3x+4y=-4\end{cases}\\ \\ \it 3x+4y=-4\ \stackrel{(*)}{\Longrightarrow}\ 3(2y-8)+4y=-4\ \Rightarrow\ 6y-24+4y=-4\ \Rightarrow\\ \\ \ \Rightarrow\ 6y+4y=24-4\ \Rightarrow\ 10y=20|_{:{10}}\ \Rightarrow\ y=2\\ \\ y=2\ \stackrel{(*)}{\Longrightarrow}\ x=2\cdot2-8=4-8=-4\\ \\ S=\{-4,\ 2\}$