Question

x+y+10=15, 5x+8y-1=0, 2x-3x+4=0, 4x-2y+6=0

Answer 1

Ma gandesc ca sunt 2 sisteme.

1) x+y+10=15
5x+8y-1=0

inmultesc prima ecuatie cu 5

si voi avea:

5x+8y-1=0
5x+5y+50=75

le scad

0+3y-1-50=0-75
3y-51=-75
3y=-75+51
3y=-24
y = - 24 : 3
y= -8

stiu ca x+y+10=15
x-8+10=15
x+2=15
x=15-2
x=13

2) 2x-3y+4=0
   4x-2y+6=0

inmultesc prima ecuatie cu 2

4x-6y+8=0
4x-2y+6=0

le scad
-6y-(-2y)+8-6=0
-6y+2y+2=0
-4y =-2
y = -2 : (-4)
y = 2:4
y = $\frac{1}{2}$

stiu ca 4x -2y +6=0

$4x-2 * \frac{1}{2} +6=0$

4x-1+6=0
4x=-6+1
4x = -5
x= $\frac{-5}{4}$