Răspuns:
Explicație pas cu pas:
a)
{2x-3y+5 = 0
{3x+y+13 = 0 <=>
-----
{2x-3y = -5
{3x+y = -13 => y = -13-3x
-------
2x+39+9x = -5 => 11x = -44 => x = -4
y = -13+42 => y = 29
==========================
b)
(x/3 + y/4 = 2
{-x+y = 1 => y = x+1
-------
{y = x+1
{⁴⁾x/3 + ³⁾(x+1)/4 = ¹²⁾2 =>
--------
{y = x+1
{4x+3x+3 = 24 => 7x = 21 => x = 3
=> y = 4
==========================
c)
{2(x+y-1) - y =-3
{3(x-y)-y = -3x <=>
-----
{2x+2y-2-y = -3
{3x-3y-y = -3x =>
-----
{2x+y = -1 => y = -1-2x
{6x-4y = 0 =>
------
6x+4+8x = 0 => 14x = -4 => x = -2/7
y = -1+4/7 => y = -3/7
===========================
d)
{(2x+y-1)/(x+2) = 2
{5x-y = 5 <=>
----
{2x+y-1 = 2x+4 ; x ≠-2
{5x-y = 5 <=>
---------
{y = 5
{5x-5 = 5 => 5x = 10 => x = 2
========================
e)
{1/x + y = 12
{1/x - 2y = 6 <=>
-----------
1/x = z =>
{z+y = 12
{z-2y = 6 => z = 2y+6 =>
----
2y+6+y = 12 => 3y = 6 => y = 2
z = 12-2 => z = 10
1/x = 10 => x = 1/10
