Răspuns:
Explicație pas cu pas:
a)
2 * x + y = 8 - 2 * x
y = 8 - 2 * x - 2 * x
y = 8 - 4 * x
3 * (x - y) - 2 * y = 29
3 * [x - (8 - 4 * x)] - 2 * (8 - 4 * x) = 29
3 * (x - 8 + 4 * x) - 16 + 8 * x = 29
3 * x - 24 + 12 * x - 16 + 8 * x = 29
15 * x + 8 * x - 24 - 16 = 29
23 * x - 40 = 29
23 * x = 29 + 40
23 * x = 69
x = 69 : 23
x = 3
y = 8 - 4 * x
y = 8 - 4 * 3
y = 8 - 12
y = -4
b)
2 * x - 5 * y = 11
2 * x = 11 + 5 * y
x = [tex]\frac{11 + 5 * y}{2}[/tex]
3 * (x + y) - 2 * x = 11
3 * ([tex]\frac{11 + 5 * y}{2}[/tex] + y) - 2 * [tex]\frac{11 + 5 * y}{2}[/tex] = 11
3 * ([tex]\frac{11 + 5 * y}{2}[/tex] + [tex]\frac{2*y}{2}[/tex]) - (11 + 5 * y) = 11
3 * [tex]\frac{11 + 7 * y}{2}[/tex] - 11 - 5 * y = 11
[tex]\frac{33 + 21 * y}{2}[/tex] - [tex]\frac{2 * 5 * y}{2}[/tex] = 11 + 11
[tex]\frac{23 - 16 * y}{2}[/tex] = 22
23 - 16 * y = 44
-16 * y = 44 - 23
y = (-21) / 16 (ceva cred ca nu este bine)
