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b: \(\dfrac{5}{7}-\dfrac{2}{3}\cdot x=\dfrac{4}{5}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{7}-\dfrac{4}{5}=\dfrac{25-28}{35}=\dfrac{-3}{35}\)
=>\(x=-\dfrac{3}{35}:\dfrac{2}{3}=\dfrac{-3}{35}\cdot\dfrac{3}{2}=-\dfrac{9}{70}\)
c: \(\dfrac{1}{2}x+\dfrac{3}{5}x=-\dfrac{2}{3}\)
=>\(x\left(\dfrac{1}{2}+\dfrac{3}{5}\right)=-\dfrac{2}{3}\)
=>\(x\cdot\dfrac{5+6}{10}=\dfrac{-2}{3}\)
=>\(x\cdot\dfrac{11}{10}=-\dfrac{2}{3}\)
=>\(x=-\dfrac{2}{3}:\dfrac{11}{10}=-\dfrac{2}{3}\cdot\dfrac{10}{11}=\dfrac{-20}{33}\)
d: \(\dfrac{4}{7}\cdot x-x=-\dfrac{9}{14}\)
=>\(\dfrac{-3}{7}\cdot x=\dfrac{-9}{14}\)
=>\(\dfrac{3}{7}\cdot x=\dfrac{9}{14}\)
=>\(x=\dfrac{9}{14}:\dfrac{3}{7}=\dfrac{9}{14}\cdot\dfrac{7}{3}=\dfrac{3}{2}\)
\(a,\frac{3}{4}-\frac{3}{4}:x=\frac{1}{2}\)
\(\frac{3}{4}:x=\frac{3}{4}-\frac{1}{2}\)
\(\frac{3}{4}:x=\frac{1}{4}\)
\(x=\frac{3}{4}:\frac{1}{4}\)
\(x=3\)
a) \(\frac{3}{4}-\frac{3}{4}:x=\frac{1}{2}\)
\(\Leftrightarrow\frac{3}{4}:x=\frac{1}{4}\Leftrightarrow x=3\)
b) \(-12.\left(x-5\right)+7.\left(3-x\right)=5\)
\(\Leftrightarrow-12x+60+21-7x=5\Leftrightarrow-19x+81=5\Leftrightarrow-19x=-76\)
\(\Leftrightarrow x=4\)
c) \(\left|7x+3\right|=66\Leftrightarrow7x+3=66\text{ hoặc }-7x-3=66\)
\(\Leftrightarrow7x=63\text{ hoặc }-7x=69\)
\(\Leftrightarrow x=9\text{ hoặc }x=-\frac{69}{7}\)
d) \(\left(x-7\right).\left(x+3\right)< 0\Leftrightarrow x-7< 0\text{ và }x+3>0\Leftrightarrow x< 7\text{ và }x>-3\)
\(\Leftrightarrow-3< x< 7\)
a ) \(-5\times\left(-x+7\right)-3\times\left(-x-5\right)=-4\times\left(12-x\right)+48\)
\(\Leftrightarrow5x-35+3x+15=-48+4x+48\)
\(\Leftrightarrow5x-3x+4x=35-15-48+48\)
\(\Leftrightarrow2x=20\)
\(\Leftrightarrow x=10\)
b ) \(-2\times\left(15-3x\right)-4\times\left(-7x+8\right)=-5-9\times\left(-2x+1\right)\)
\(\Leftrightarrow-30+6x-28x-32=-5+18x-9\)
\(\Leftrightarrow6x-28x-18x=30+32-5-9\)
\(\Leftrightarrow-40x=48\)
\(\Leftrightarrow x=-1.2\)
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
a) 3/4-3/4:x=1/2
=>3/4:x=3/4-1/2
=>3/4:x=3/4-2/4
=>3/4:x=1/4
=>x=3/4:1/4
=>x=3/4.4/1
=>x=4
b)-12.(x-5)+7.(3-x)=5
=>-12x+60+21-7x=5
=>81-19x=5
=>19x=81-5
=>19x=76
=>x=76:19
=>x=4
c) |7x+3|=66
=>7x+3=-66 hoặc 7x+3=66
+)Nếu 7x+3=-66
=>7x=-66-3=-66+(-3)=-69
=>x=(-69):7=\(\frac{-69}{7}\)
+)Nếu 7x+3=66
=>7x=66-3=63
=>x=x=63:7=9
d)(x-7)(x+3)<0
=>x-7<0 hoặc x+3<0
+)/nếu x-7<0
=>x<7
+)nếu x+3<0
=>x<-3