Câu 1:
a) 4x-2+4xy+y=2
y(4x+1)+4x+1-3=2
y(4x+1)+(4x+1) = 5
(4x+1)(y+1) =5
Ta có: 5=1.5=5.1=-1.(-5)=-5.(-1)
Với $\left \{ {{4x+1=1} \atop {y+1=5}} \right.$
=> $\left \{ {{x=0} \atop {y=4}} \right.$ ( T/M)
Với $\left \{ {{4x+1=5} \atop {y+1=1}} \right.$
=> $\left \{ {{x=1} \atop {y=0}} \right.$ ( T/M)
Với $\left \{ {{4x+1=-5} \atop {y+1=-1}} \right.$
=> $\left \{ {{x=-3/2} \atop {y=-2}} \right.$ ( Loại )
Với $\left \{ {{4x+1=-1} \atop {y+1=-5}} \right.$
=> $\left \{ {{x=-1/2} \atop {y=-6}} \right.$ ( Loại )
b) 2xy + y+4x-3=0
y(2x + 1) + 4x+2-5=0
y(2x + 1) + 2(2x+1) = 5
(2x + 1)(y+2) =5
Ta có : 5=1.5=5.1=-1.(-5)=-5.(-1)
Với $\left \{ {{2x+1=1} \atop {y+2=5}} \right.$
=> $\left \{ {{x=0} \atop {y=3}} \right.$ ( T/M)
Với $\left \{ {{2x+1=5} \atop {y+2=1}} \right.$
=> $\left \{ {{x=2} \atop {y=-1}} \right.$ ( T/M)
Với $\left \{ {{2x+1=-5} \atop {y+2=-1}} \right.$
=> $\left \{ {{x=-3} \atop {y=-3}} \right.$ ( T/M)
Với $\left \{ {{2x+1=-1} \atop {y+2=-5}} \right.$
=> $\left \{ {{x=-1} \atop {y=-7}} \right.$ ( T/M)
Câu 2:
a) 2x² -5x -7 =0
2x² - 2x +7x-7=0
2x(x-1) + 7(x-1)=0
(x-1)(2x+7) = 0
=> \(\left[ \begin{array}{l}x-1=0\\2x+7=0\end{array} \right.\)
=> \(\left[ \begin{array}{l}x=1\\x=-7/2\end{array} \right.\)
b) 3x ² -5x+2=0
3x² - 3x - 2x+2=0
3x(x-1) -2(x-1) = 0
(x-1)(3x-2) = 0
=>\(\left[ \begin{array}{l}x-1=0\\3x-2=0\end{array} \right.\)
=> \(\left[ \begin{array}{l}x=1\\x=2/3\end{array} \right.\)
Xin hay nhất
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