

Báo cáo sai phạm
a)2x+1.3y=12x
=>2x+3y=(3.4)x=3x.22x
=>3y-x=2x-1
=>y-x=x-1=0
=>x=y=1
b)10x:5y=20y
=>10x=20y.5y
=>10x=100y
=>10x=(102)y
=>10x=102y
=>x=2y
=>y=2x
c)2x=4y-1
=>2x=(22)y-1=22.(y-1)=22y-2
=>x=2y-2(1)
27y=3x+8
=>(33)y=3x+8=33y
=>x+8=3y(2)
thay 1 vao 2 ta co:
3y=2y-2+8
=>3y-2y=6
=>y=6
=>x=2y-2=2.6-2=12-2=10
=>x=6
y=10