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Câu a :
\(\dfrac{x}{4}=\dfrac{16}{128}\) \(\Leftrightarrow x.128=4.16\) \(\Rightarrow x=\dfrac{1}{2}\)
Câu b :
\(1\dfrac{5}{6}=-\dfrac{x}{5}\) \(\Leftrightarrow11.5=-x.6\) \(\) \(\Rightarrow-x=-\dfrac{55}{6}\)
Câu c :
\(\dfrac{4,25}{8}=\dfrac{-3,5}{x}\) \(\Leftrightarrow4,25.x=8.-3,5\) \(\Rightarrow x=-\dfrac{112}{17}\)
a,Ta có : x.128=16.4
x.128=64
Suy ra : x=1/2
b,\(1\dfrac{5}{6}=\dfrac{11}{6}\)
Ta có ; 11.5=-x.6
-x.6=55
Suy ra : x=-55/6
c,Ta có : 4,25.x=-3,5.8
4,25.x=-28
Suy ra : x=-112/17
a) \(\dfrac{x}{4}=\dfrac{16}{128}\Rightarrow x=\dfrac{4.16}{128}=\dfrac{1}{2}=0,5\)
b)\(1\dfrac{5}{6}=\dfrac{-x}{5}\\ \Leftrightarrow\dfrac{11}{6}=\dfrac{-x}{5}\Rightarrow-x=\dfrac{5.11}{6}=\dfrac{55}{6}\Rightarrow x=-\dfrac{55}{6}\)
c) \(\dfrac{4,25}{8}=\dfrac{-3,5}{x}\Rightarrow x=\dfrac{8.\left(-3,5\right)}{4,25}=-\dfrac{112}{17}\)
a,X/4=16/28
=»x/4=4/7
=4/7.4
=7
b,1/5/6=-x/5
-x/5=11/6
X=11/6.5
X=55/6
\(a,\dfrac{x}{4}=\dfrac{16}{128}\\ \Leftrightarrow128x=4.16\\ \Leftrightarrow128x=64\\ \Leftrightarrow x=\dfrac{1}{2}\)
Vậy...
\(b,1\dfrac{5}{6}=\dfrac{-x}{5}\\ \Leftrightarrow-6x=25\\ \Leftrightarrow x=-\dfrac{25}{6}\)
Vậy...
\(c,4,25:8=-3,5:x\\ \Leftrightarrow4,25x=-3,5.8\\ \Leftrightarrow x=-28:4,25\\ \Leftrightarrow x=-\dfrac{112}{17}\)
Vậy...
a.
| x | = 5,6
=>\(\left[{}\begin{matrix}x=5,6\\x=-5,6\end{matrix}\right.\)
Vậy \(x\in\left\{-5,6;5,6\right\}\)
b, \(\left|x-3,5\right|=5\)
=>\(\left[{}\begin{matrix}x-3,5=5\\x-3,5=-5\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=8,5\\x=-1,5\end{matrix}\right.\)
Vậy \(x\in\left\{-1,5;8,5\right\}\)
c,\(\left|x-\dfrac{3}{4}\right|-\dfrac{1}{2}=0\)
=> \(\left|x-\dfrac{3}{4}\right|=\dfrac{1}{2}\)
=>\(\left[{}\begin{matrix}x-\dfrac{3}{4}=\dfrac{1}{2}\\x-\dfrac{3}{4}=-\dfrac{1}{2}\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{1}{4}\end{matrix}\right.\)
Vậy \(x\in\left\{\dfrac{1}{4};\dfrac{5}{4}\right\}\)
d,\(\left|4x\right|-\left(\left|-13,5\right|\right)=\left|\dfrac{1}{4}\right|\)
=> \(\left|4x\right|-13,5=\dfrac{1}{4}\)
=> \(\left|4x\right|=13,75\)
=>\(\left[{}\begin{matrix}4x=13,75\\4x=-13,75\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=3,4375\\x=-3,4375\end{matrix}\right.\)
Vậy \(x\in\left\{-3,4375;3,4375\right\}\)
e, ( x - 1 ) 3 = 27
=> x - 1 = 3
=> x = 4
Vậy x = 4
f, ( 2x - 3)2 = 36
=> \(\left[{}\begin{matrix}2x-3=6\\2x-3=-6\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=4,5\\x=-1,5\end{matrix}\right.\)
Vậy x\(\in\left\{-1,5;4,5\right\}\)
g, \(5^{x+2}=625\)
=> \(5^{x+2}=5^4\)
=> x + 2 = 4
=> x = 2
Vậy x = 2
h, ( 2x - 1)3 = -8
=> 2x - 1 = -2
=> x = \(\dfrac{-1}{2}\)
Vậy x = \(\dfrac{-1}{2}\)
i, \(\dfrac{1}{4}.\dfrac{2}{6}.\dfrac{3}{8}.\dfrac{4}{10}.\dfrac{5}{12}...\dfrac{30}{62}.\dfrac{31}{64}=2^x\)
=> \(\dfrac{1.2.3.4.5...30.31}{4.6.8.10.12...62.64}=2^x\)
=>\(\dfrac{1.2.3.4.5...30.31}{\left(2.3.4.5...30.31.32\right)\left(2.2.2.2...2.2_{ }\right)}=2^x\)(có 31 số 2)
=> \(\dfrac{1}{32.2^{31}}=2^x\)
=> \(\dfrac{1}{2^{36}}=2^x\)
=> x = -36
Vậy x = -36
\(a.\)
\(\dfrac{x}{4}=\dfrac{16}{128}\)
\(\Rightarrow x=\dfrac{16.4}{128}=\dfrac{1}{2}\)
\(b.\)
\(1\dfrac{5}{6}=-\dfrac{x}{5}\)
\(\Rightarrow\dfrac{11}{6}=-\dfrac{x}{5}\)
\(\Rightarrow x=\dfrac{11.\left(-5\right)}{6}=-\dfrac{55}{6}\)
\(c.\)
\(4,25:8=-3,5:x\)
\(\Rightarrow\dfrac{4,25}{8}=\dfrac{-3,5}{x}\)
\(\Rightarrow x=\dfrac{-3,5.8}{4,25}=-\dfrac{112}{17}\)
\(a)\dfrac{x}{4}=\dfrac{16}{128}\)
\(\Rightarrow\dfrac{16}{128}.4=\dfrac{1}{2}\)
\(b)1\dfrac{5}{6}=\dfrac{-x}{5}\)
\(\Rightarrow x=\dfrac{11}{6}.\left(-5\right)=\dfrac{-55}{6}\)
\(c)4,25:8=-3,5:x\)
\(\Rightarrow\dfrac{4,25}{8}=\dfrac{-3,5}{x}\)
\(\Rightarrow x=\dfrac{-3,5.8}{4,25}=\dfrac{-112}{17}\)
Chúc bạn học tốt!
câu E
\(\left\{{}\begin{matrix}x\ne\dfrac{5}{2}\\\left(2x-5\right)\left(5-2x\right)=-\left(\dfrac{3}{2}\right)^4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ne\dfrac{5}{2}\\\left|2x-5\right|=\left(\dfrac{3}{2}\right)^2\end{matrix}\right.\)
\(\left[{}\begin{matrix}\left\{{}\begin{matrix}x< \dfrac{5}{2}\\2x-5=-\left(\dfrac{3}{2}\right)^2\Rightarrow x=\dfrac{11}{8}< \dfrac{5}{2}\left(n\right)\end{matrix}\right.\\\left\{{}\begin{matrix}x>\dfrac{5}{2}\\2x-5=\left(\dfrac{3}{2}\right)^2\Rightarrow x=\dfrac{29}{8}>\dfrac{5}{2}\left(n\right)\end{matrix}\right.\end{matrix}\right.\)
câu F (bạn cho vào lớp 7.2=lớp 14 nhé. )
a: \(\left|x\right|=3+\dfrac{1}{5}=\dfrac{16}{5}\)
mà x<0
nên x=-16/5
b: \(\left|x\right|=-2.1\)
nên \(x\in\varnothing\)
c: \(\left|x-3.5\right|=5\)
=>x-3,5=5 hoặc x-3,5=-5
=>x=8,5 hoặc x=-1,5
d: \(\left|x+\dfrac{3}{4}\right|-\dfrac{1}{2}=0\)
=>|x+3/4|=1/2
=>x+3/4=1/2 hoặc x+3/4=-1/2
=>x=-1/4 hoặc x=-5/4
a)\(\dfrac{x}{4}=\dfrac{16}{128}\)
\(\Leftrightarrow\dfrac{x}{4}=\dfrac{1}{8}\)
\(\Rightarrow x=\dfrac{1.4}{8}=\dfrac{1}{2}\)
b)\(1\dfrac{5}{6}=\dfrac{-x}{5}\)
\(\Leftrightarrow\dfrac{11}{6}=\dfrac{-x}{5}\)
\(\Rightarrow-x=\dfrac{11.5}{6}=\dfrac{-55}{6}\)
c)\(4,25:8=-3,5:x\)
\(\Leftrightarrow\dfrac{17}{32}=\dfrac{-3,5}{x}\)
\(\Rightarrow x=\dfrac{\left(-3,5\right).32}{17}=-\dfrac{112}{17}\)
Tìm x
a)\(\dfrac{x}{4}\)=\(\dfrac{16}{128}\)
\(\Rightarrow\)x.128=16.4
x.128=64
x=64:128
x=\(\dfrac{1}{2}\)
Vậy x=\(\dfrac{1}{2}\)
b)\(1\dfrac{5}{6}\)=\(\dfrac{-x}{5}\)
\(\dfrac{11}{6}\)=\(\dfrac{-x}{5}\)
-x:5=\(\dfrac{11}{6}\)
-x=\(\dfrac{11}{6}\).5
-x=\(\dfrac{55}{6}\)
\(\Rightarrow\)x=\(\dfrac{-55}{6}\)
Vậy x=\(\dfrac{-55}{6}\)
c)4,25:8 = -3,5:x
-3,5:x=\(\dfrac{17}{4}\)
x=-3,5:\(\dfrac{17}{4}\)
x=\(\dfrac{14}{17}\)
Vậy x=\(\dfrac{14}{17}\)
1.Tính
a.\(\dfrac{7}{23}\left[(-\dfrac{8}{6})-\dfrac{45}{18}\right]=\dfrac{7}{23}.-\dfrac{12}{6}=-\dfrac{7}{6}\)
b.\(\dfrac{1}{5}\div\dfrac{1}{10}-\dfrac{1}{3}(\dfrac{6}{5}-\dfrac{9}{4})=2-(-\dfrac{7}{20})=\dfrac{47}{20}\)
c.\(\dfrac{3}{5}.(-\dfrac{8}{3})-\dfrac{3}{5}\div(-6)=-\dfrac{3}{2}\)
d.\(\dfrac{1}{2}.(\dfrac{4}{3}+\dfrac{2}{5})-\dfrac{3}{4}.(\dfrac{8}{9}+\dfrac{16}{3})=-\dfrac{19}{5}\)
e.\(\dfrac{6}{7}\div(\dfrac{3}{26}-\dfrac{3}{13})+\dfrac{6}{7}.(\dfrac{1}{10}-\dfrac{8}{5})=-\dfrac{61}{7}\)
Bài 2
a.\(1^2_5x+\dfrac{3}{7}=\dfrac{4}{5}\)
\(x=\dfrac{13}{49}\)
b.\(\left|x-1,5\right|=2\)
Xảy ra 2 trường hợp
TH1
\(x-1,5=2\)
\(x=3,5\)
TH2
\(x-1,5=-2\)
\(x=-0,5\)
Vậy \(x=3,5\) hoặc \(x=-0,5\) .
Ngại làm quá trời ơi,lần sau bn tách ra nhá làm vậy mỏi tay quá.
a) \(\left|x\right|=3,5\)
\(\Rightarrow\left[{}\begin{matrix}x=3,5\\x=-3,5\end{matrix}\right.\)
b) \(\left|1-x\right|+0,73=3\)
\(\Rightarrow\left|1-x\right|=3-0,73\)
\(\Rightarrow\left|1-x\right|=2,27\)
\(\Rightarrow\left[{}\begin{matrix}1-x=2,27\\1-x=-2,27\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-1,27\\x=3,27\end{matrix}\right.\)
c) \(\dfrac{-5}{8}+x=\dfrac{4}{9}\)
\(\Rightarrow x=\dfrac{4}{9}-\left(\dfrac{-5}{8}\right)\)
\(\Rightarrow x=\dfrac{77}{72}\)