7B.a) [tex]\frac{2x-1}{x}=\frac{4}{3}\Rightarrow 4x=3(2x-1)=6x-3\Rightarrow 3=6x-4x=2x\Rightarrow x=\frac{3}{2}(loại)[/tex]
Vậy không tồn tại x nguyên.
b) [tex]\frac{2x-1}{3}=\frac{3x+1}{4}\Rightarrow 4(2x-1)=3(3x+1)\Rightarrow 8x-4=9x+3\Rightarrow 9x-8x=-4-3\Rightarrow x=-7[/tex]
c) [tex]\frac{4}{x+2}=\frac{7}{3x+1}\Rightarrow 7(x+2)=4(3x+1)\Rightarrow 7x+14=12x+4\Rightarrow 12x-7x=14-4\Rightarrow 5x=10\Rightarrow x=2[/tex]
d) [tex]\frac{-3}{x+1}=\frac{4}{2-2x}=\frac{4}{2(1-x)}=\frac{2}{1-x}\Rightarrow -3(1-x)=2(x+1)\Rightarrow 3x-3=2x+2\Rightarrow 3x-2x=2+3\Rightarrow x=5[/tex]
9B. a) [tex]x+y=10\Rightarrow 3x+3y=30\Rightarrow 2y+3y=30\Rightarrow 5y=30\Rightarrow y=6\Rightarrow x=\frac{2}{3}y=4[/tex]
b) [tex]\frac{x-2}{y+3}=\frac{4}{6}=\frac{2}{3}\Rightarrow 2(y+3)=3(x-2)\Rightarrow 2y+6=3x-6\Rightarrow 3x=2y+6+6=2y+12[/tex]
Lại có: [tex]y-x=-4\Rightarrow \Rightarrow 3y-3x=-12\Rightarrow 3y-(2y+12)=-12\Rightarrow y-12=-12\Rightarrow y=0\Rightarrow x=4[/tex]
c) [tex]\frac{x}{4}=\frac{y}{-10}\Rightarrow -10x=4y\Rightarrow 5x=-2y\Rightarrow 12=x+2y=x-5x=-4x\Rightarrow x=-3\Rightarrow y=\frac{15}{2}[/tex]
[TẶNG BẠN] TRỌN BỘ Bí kíp học tốt 08 môn
