Question

Решите систему уравнений, методом подстановки.

А )
х=5у-6
3х-4у=4


Б)
4х-5у=-2
3х+2у=-13

Answer 1

A.
$left { {{x=5y-6} atop {3x-4y=4}} right. \ \ left { {{x=5y-6} atop {3cdot (5y-6)-4y=4}} right. \ \ left { {{x=5y-6} atop {15y-18-4y=4}} right. \ \ left { {{x=5y-6} atop {11y=22}} right. \ \ left { {{x=10-6} atop {y=2}} right. \ \ left { {{x=4} atop {y=2}} right.$
Б.
$left { {{4x-5y=-2} atop {3x+2y=-13}} right. \ \ left { {{4x-5y=-2} atop {y= frac{ -13-3x}{2}}} right. \ \ left { {{4x-5cdot( frac{ -13-3x}{2}) =-2} atop {y= frac{ -13-3x}{2}}} right. \ \ left { {{8x-5cdot( -13-3x) =-4} atop {y= frac{ -13-3x}{2}}} right. \ \ left { {{8x+65+15x) =-4} atop {y= frac{ -13-3x}{2}}} right. \ \ left { {{23x=69} atop {y= frac{ -13-3x}{2}}} right. \ \ left { {{x=3} atop {y= frac{ -13-3cdot 3}{2}}} right.$
$left { {{x=3} atop {y= frac{ -24}{2}}} right. \ \ left { {{x=3} atop {y= -12}} right.$