a) x + 3 = 2x - 4( x - 3)
⇔ x + 3 = 2x - 4x + 12
⇔ x + 2x = 9
⇔ 3x = 9
⇔ x = 3
KL...
b) \(\dfrac{x}{x-2}-\dfrac{x+2}{x-1}=0\) ( x # 2 ; x # 1)
⇔ x( x - 1) - ( x + 2)( x - 2) = 0
⇔ x2 - x - ( x2 - 4) = 0
⇔ 4 - x = 0
⇔ x = 4 ( TM ĐKXĐ )
KL...
Giải:
a) \(x+3=2x-4\left(x-3\right)\)
\(\Leftrightarrow x+3=2x-4x+12\)
\(\Leftrightarrow x+3=-2x+12\)
\(\Leftrightarrow x+2x=12-3\)
\(\Leftrightarrow3x=9\)
\(\Leftrightarrow x=3\)
Vậy ...
b) \(\dfrac{x}{x-2}-\dfrac{x+2}{x-1}=0\left(1\right)\)
ĐKXĐ: \(x\ne2;x\ne1\)
\(\left(1\right)\Leftrightarrow\dfrac{x\left(x-1\right)}{\left(x-2\right)\left(x-1\right)}-\dfrac{\left(x+2\right)\left(x-2\right)}{\left(x-2\right)\left(x-1\right)}=0\)
\(\Rightarrow x\left(x-1\right)-\left(x+2\right)\left(x-2\right)=0\)
\(\Leftrightarrow x^2-x-\left(x^2-4\right)=0\)
\(\Leftrightarrow x^2-x-x^2+4=0\)
\(\Leftrightarrow-x+4=0\)
\(\Leftrightarrow-x=-4\)
\(\Leftrightarrow x=4\) (thoả mãn)
Vậy ...
x + 3 = 2x - 4 ( x - 3 )
x + 3 = 2x - 4x - 12
x + 3 = x . ( 2 - 4 ) - 12
x + 3 = x . -2 - 12
x - x . -2 = 12- 3
x. [1 - (-2)] = 9
x. 3 = 9
x = 9 : 3
x = 3
vậy x = 3
b, x/x-2 - x + 2/x-1 = 0
+ x/x-2 = 0 hoặc x + 2/ x - 1 = 0
+TH1 x/x-2 = 0
+ x/-2 + 2/ x-2 = 0
+ 1 + 2/x-2 = 0
+ 2/x-2 = 0-1
+2/x-2 = 2/-2
+ x - 2 = -2
x = -2 + 2
x = 0
+TH2 : x + 2/ x -1 = 0
x - 1 + 3/ x - 1 = 0
1 + 3/x - 1 = 0
3/x-1 = 0 - 1
3/x-1 =-1
3/x-1 = 3/-3
x - 1 = -3
x = -3 + 1
x = -2
vậy x = 0 hoặc x = -2
tick cho mình nhé
