Toán Lớp 6: tìm x, biết : l 3 / 5 – 1 / 2. x l > 2/5
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Toán Lớp 6: tìm x, biết : l 3 / 5 – 1 / 2. x l > 2/5
Comments ( 1 )
#Rick
|3/5-1/2 xx x|>2/5
=>\(\left[ \begin{array}{l}\dfrac{3}{5}-\dfrac{1}{2}\times x >\dfrac{2}{5}\\\dfrac{3}{5}-\dfrac{1}{2}\times x< -\dfrac{2}{5}\end{array} \right.\)
*Giải 3/5-1/2xx x>2/5:
=>10xx3/5-10xx1/2x>10xx2/5
=>2xx3-5x>2xx2
=>6-5x>4
=>-5x>4-6
=>-5x> -2
=>x<(-2)/(-5)
=>x<2/5
*Giải 3/5-1/2xx x< -2/5:
=>3/5-x/2< -2/5
=>-x/2<-2/5-3/5
=>10(-x/2)<-10xx2/5-10xx3/5
=>-5x<-2xx2-2xx3
=>-5x<-4-6
=>-5x<-10
=>x>(-10)/(-5)
=>x>2
=>\(\left[ \begin{array}{l}x<\dfrac{2}{5}\\x>2\end{array} \right.\)
Vậy x<2/5 hoặc x>2