\(\dfrac{6}{5}x\dfrac{15}{2}\)
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`x xx4/5 :2=6/7`
`x xx 4/5xx1/2=6/7`
`x xx2/5=6/7`
`x=6/7:2/5`
`x=6/7xx5/2`
`x=15/7`
b)
`6/5:x:5/4=10/15`
`6/5:x xx4/5=2/3`
`6/5:x=2/3:4/5`
`6/5:x=2/3xx5/4`
`6/5:x=5/6`
`x=6/5:5/6`
`x=6/5xx6/5`
`x=36/25`
a) x × 4/5 : 2 = 6/7
x × 4/5 = 6/7 × 2
x × 4/5 = 12/7
x = 12/7 : 4/5
x = 15/7
b) 6/5 : x : 5/4 = 10/15
6/5 : x : 5/4 = 2/3
6/5 : x = 2/3 × 5/4
6/5 : x = 5/6
x = 6/5 : 5/6
x = 36/25
a) Ta có: \(\dfrac{2x-1}{5}-\dfrac{x-2}{3}=\dfrac{x+7}{15}\)
\(\Leftrightarrow\dfrac{3\left(2x-1\right)}{15}-\dfrac{5\left(x-2\right)}{15}=\dfrac{x+7}{15}\)
\(\Leftrightarrow6x-3-5x+10-x-7=0\)
\(\Leftrightarrow0x=0\)(luôn đúng)
Vậy: S={x|\(x\in R\)}
a)\(x=\left(\dfrac{3}{56}\cdot\dfrac{28}{9}\right):\dfrac{-3}{7}=\dfrac{1}{6}:\dfrac{-3}{7}=-\dfrac{7}{18}\)
b)\(x=\left(\dfrac{7}{15}\cdot\dfrac{5}{3}\right)+\dfrac{3}{16}=\dfrac{7}{9}+\dfrac{3}{16}=\dfrac{139}{144}\)
\(\dfrac{3}{5}+\dfrac{1}{2}+\dfrac{8}{15}\\ =\dfrac{3\times6}{5\times6}+\dfrac{1\times15}{2\times15}+\dfrac{8\times2}{15\times2}\\ =\dfrac{18}{30}+\dfrac{15}{30}+\dfrac{16}{30}\\ =\dfrac{49}{30}\\ \dfrac{6}{9}+\dfrac{14}{18}-\dfrac{5}{6}\\ =\dfrac{6\times2}{9\times2}+\dfrac{14}{18}-\dfrac{5\times3}{6\times3}\\ =\dfrac{12}{18}+\dfrac{14}{18}-\dfrac{15}{18}\\ =\dfrac{11}{18}\)
\(\dfrac{9}{20}-\dfrac{3}{5}:\dfrac{4}{1}\\ =\dfrac{9}{20}-\dfrac{3}{5}\times\dfrac{1}{4}\\ =\dfrac{9}{20}-\dfrac{3}{20}\\ =\dfrac{6}{20}\\ =\dfrac{3}{10}\)
\(\dfrac{1}{6}+\dfrac{2}{3}\times\dfrac{8}{9}\\=\dfrac{1}{6}+\dfrac{16}{27}\\ =\dfrac{1\times9}{6\times9}+\dfrac{16\times2}{27\times2}\\ =\dfrac{9}{54}+\dfrac{32}{54}\\ =\dfrac{41}{54}.\)
a: =>3/5x=5/6+3/2=5/6+9/6=14/6=7/3
=>x=35/9
b: =(4/5+16/5)+(37/7+57)
=61+37/7=464/7
\(\dfrac{3}{5}x=\dfrac{5}{6}+\dfrac{3}{2}=\dfrac{14}{6}=\dfrac{7}{3}\Leftrightarrow x=\dfrac{7}{3}:\dfrac{3}{5}=\dfrac{35}{9}\)
\(\dfrac{19}{5}+\dfrac{37}{7}+57=\dfrac{19.7+37.5}{35}+\dfrac{57.35}{35}=\dfrac{2313}{35}\)
a) (2x - 3)(6 - 2x) = 0
=> \(\left[{}\begin{matrix}2x-3=0\\6-2x=0\end{matrix}\right.=>\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)
b) \(5\dfrac{4}{7}:x=13=>\dfrac{39}{7}:x=13=>x=\dfrac{39}{7}:13=>x=\dfrac{3}{7}\)
c) \(2x-\dfrac{3}{7}=6\dfrac{2}{7}=>2x-\dfrac{3}{7}=\dfrac{44}{7}=>2x=\dfrac{47}{7}=>x=\dfrac{47}{14}\)
d) \(\dfrac{x}{5}+\dfrac{1}{2}=\dfrac{6}{10}=>\dfrac{x}{5}=\dfrac{6}{10}-\dfrac{1}{2}=>\dfrac{x}{5}=\dfrac{1}{10}=>x.10=5=>x=\dfrac{1}{2}\)
e) \(\dfrac{x+3}{15}=\dfrac{1}{3}=>\left(x+3\right).3=15=>x+3=5=>x=2\)
a, -4\(\dfrac{3}{5}\).2\(\dfrac{4}{3}\) < \(x\) < -2\(\dfrac{3}{5}\): 1\(\dfrac{6}{15}\)
- \(\dfrac{23}{5}\).\(\dfrac{10}{3}\) < \(x\) < - \(\dfrac{13}{5}\): \(\dfrac{21}{15}\)
- \(\dfrac{46}{3}\) < \(x\) < - \(\dfrac{13}{7}\)
\(x\) \(\in\) {-15; -14;-13;..; -2}
a) Ta có \(-4\dfrac{3}{5}\cdot2\dfrac{4}{3}=-\dfrac{23}{5}\cdot\dfrac{10}{3}=-\dfrac{46}{3}\) và \(-2\dfrac{3}{5}\div1\dfrac{6}{15}=-\dfrac{13}{5}\div\dfrac{7}{5}=-\dfrac{13}{7}\)
Do đó \(-\dfrac{46}{3}< x< -\dfrac{13}{7}\)
Lại có \(-\dfrac{46}{3}\le-15\) và \(-\dfrac{13}{7}\ge-2\)
Suy ra \(-15\le x\le-2\), x ϵ Z
b) Ta có \(-4\dfrac{1}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=-\dfrac{13}{3}\cdot\dfrac{1}{3}=-\dfrac{13}{9}\) và \(-\dfrac{2}{3}\left(\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{3}{4}\right)=-\dfrac{2}{3}\cdot\dfrac{-11}{12}=\dfrac{11}{18}\)
Do đó \(-\dfrac{13}{9}< x< \dfrac{11}{18}\)
Lại có \(-\dfrac{13}{9}\le-1\) và \(\dfrac{11}{18}\ge0\)
Suy ra \(-1\le x\le0\), x ϵ Z
60x [7/12+4/15]
60x153/180
=9180/180
b 1/2x2/3x3/4x4/5x5/6x6/7x7/8x8/9=40320/4032
a: \(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=2\\x+\dfrac{1}{5}=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{9}{5}\\x=-\dfrac{11}{5}\end{matrix}\right.\)
\(a,\left|x+\dfrac{1}{5}\right|-4=-2\\ \left|x+\dfrac{1}{5}\right|=\left(-2\right)+4\\ \left|x+\dfrac{1}{5}\right|=2\Rightarrow x+\dfrac{1}{5}=2\)
hoặc \(x+\dfrac{1}{5}=-2\)
Với \(x+\dfrac{1}{5}=2\Rightarrow x=2-\dfrac{1}{5}\)hay \(x=\dfrac{9}{5}\)
Với \(x+\dfrac{1}{5}=-2\Rightarrow x=-2-\dfrac{1}{5}\)hay \(x=-\dfrac{11}{5}\)
Thông cảm . bt làm mỗi câu a
\(\dfrac{6}{5}\times\dfrac{15}{2}=\dfrac{6\times15}{5\times2}=9\)
9