Question

Rezolvati in RxR prin metoda substitutiei sistemul de ecuatii
a...x-3y=0 
   5x-y=-1


b...2x-y=1
6x+2y=0

Answer 1

a)

$x-3y = 0 \\5x-y= -1 \\\\x = 3y \\5*3y-y=-1\\\\x=3y\\15y-y= -1\\\\x=3y\\y= \frac{-1}{14} \\\\x=3*\frac{-1}{14} = \frac{-3}{14}$

b)

$2x-y=1\\6x+2y=0 \\\\y=2x-1\\6x+2(2x-1)=0\\\\y=2x-1\\6x+4x-2=0\\\\y=2x-1\\10x=2\\\\y=2x-1\\x=\frac{2}{10}= \frac{1}{5} \\\\y=2*\frac{1}{5} -1 = \frac{2}{5} - \frac{5}{5} = \frac{-3}{5}$