Toán Lớp 6: a) 1/2x-1/2=-2/5
b) x-1/5=1/6+ -7/30
c) 1/2x+1/5x= -17/30
giúp mình vs nhé
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Toán Lớp 6: a) 1/2x-1/2=-2/5
b) x-1/5=1/6+ -7/30
c) 1/2x+1/5x= -17/30
giúp mình vs nhé
Comments ( 2 )
$a)$ $\dfrac{1}{2}x-\dfrac{1}{2}=-\dfrac{2}{5}$
$⇒\dfrac{1}{2}x-\dfrac{1}{2}+\dfrac{1}{2}=-\dfrac{2}{5}+\dfrac{1}{2}$
$⇒\dfrac{1}{2}x=\dfrac{1}{10}$
$⇒2\cdot \dfrac{1}{2}x=\dfrac{1\cdot \:2}{10}$
$⇒x=\dfrac{1}{5}$
Vậy $x=\dfrac{1}{5}$
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$b)$ $x-\dfrac{1}{5}=\dfrac{1}{6}+\dfrac{\left(-7\right)}{30}$
$⇒x-\dfrac{1}{5}=\dfrac{1}{6}-\dfrac{7}{30}$
$⇒x-\dfrac{1}{5}=\dfrac{5}{30}-\dfrac{7}{30}$
$⇒x-\dfrac{1}{5}=\dfrac{5-7}{30}$
$⇒x-\dfrac{1}{5}=\dfrac{-2}{30}$
$⇒x-\dfrac{1}{5}=-\dfrac{1}{15}$
$⇒x-\dfrac{1}{5}+\dfrac{1}{5}=-\dfrac{1}{15}+\dfrac{1}{5}$
$⇒x=\dfrac{2}{15}$
Vậy $x=\dfrac{2}{15}$
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$c)$ $\dfrac{1}{2}x+\dfrac{1}{5}x=-\dfrac{17}{30}$
$⇒\dfrac{1}{2}x\cdot \:30+\dfrac{1}{5}x\cdot \:30=-\dfrac{17}{30}\cdot \:30$
$⇒21x=-17$
$⇒x=-\dfrac{17}{21}$
Vậy $x=-\dfrac{17}{21}$
Giải đáp + Lời giải và giải thích chi tiết:
a)
1/2x-1/2=-2/5
=>1/2x=-2/5+1/2
=>1/2x=-4/10+5/10
=>1/2x=1/10
=>x=1/10:1/2
=>x=1/10 .2
=>x=1/5
Vậy x=1/5
b)
x-1/5=1/6+(-7/30)
=>x-1/5=5/30+(-7/30)
=>x-1/5=-1/15
=>x=-1/15+1/5
=>x=-1/15+3/15
=>x=2/15
Vậy x=2/15
c)
1/2x+1/5x=-17/30
=>x.(1/2+1/5)=-17/30
=>x.(5/10+2/10)=-17/30
=>x. 7/10=-17/30
=>x=(-17/30):7/10
=>x=(-17/30). 10/7
=>x=-17/21
Vậy x=-17/21