Question

Oblicz metodą podstawiania a ) x-3y= -5 2x=5y=1 b) 2x-3y=7 4x + 1/2y=1 C )4x-6y=0 2/3 +1/3 y = 1/3

Answer 1

A )
x-3y= -5
2x+5y=1

x=-5+3y
2(-5+3y)+5y=1
-10+6y+5y=1
11y=11
y=1

x=-5+3*1
x=-5+3
x=-2

spr:
x-3y= -5
-2-3*1=-5
-2-3=-5
-5=-5


b)
2x-3y=7
4x + 1/2y=1 |:½

2x-3y=7
y=2-8x

2x-3(2-8x)=7
2x-6+24x=7
26x=13
x=0,5

y=2-8*0,5
y=2-4
y=-2

spr:
2x-3y=7
2*0,5-3*(-2)=7
1+6=7
7=7



C )
4x-6y=0
2/3 +1/3 y = 1/3|:⅓

4x-6y=0
y=1-2x

4x-6(1-2x)=0
4x-6+12x=0
16x=6
x=⅜

y=1-2*⅜
y=1-¾
y=¼

spr:
4x-6y=0
4*⅜-6*¼=0
1,5-1,5=0
0=0