a) 9/4 - 1,2 + 1/4 b) 1/3 + 1,5 - 1/4
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NV
5 tháng 8 2023
a) \(2^x=8\)
⇔ \(2^x=2^3\)
⇒ \(x=3\)
b) \(3^x=27\)
⇔ \(3^x=3^3\)
⇒ \(x=3\)
c) \(\left(-\dfrac{1}{2}\right)x=\left(-\dfrac{1}{2}\right)^4\)
⇔ \(x=\left(-\dfrac{1}{2}\right)^4\div\left(-\dfrac{1}{2}\right)\)
⇔ \(x=\left(-\dfrac{1}{2}\right)^3\)
d) \(x\div\left(-\dfrac{3}{4}\right)=\left(-\dfrac{3}{4}\right)^2\)
⇔ \(x=\left(-\dfrac{3}{4}\right)^2\cdot\left(-\dfrac{3}{4}\right)\)
⇔ \(x=\left(-\dfrac{3}{4}\right)^3=-\dfrac{27}{64}\)
d) \(\left(x+1\right)^3=-125\)
⇔ \(\left(x+1\right)^3=\left(-5\right)^3\)
⇔ \(x+1=-5\)
⇔ \(x=-5-1=-6\)
5 tháng 8 2023
2:
a: (x-1,2)^2=4
=>x-1,2=2 hoặc x-1,2=-2
=>x=3,2(loại) hoặc x=-0,8(loại)
b: (x-1,5)^2=9
=>x-1,5=3 hoặc x-1,5=-3
=>x=-1,5(loại) hoặc x=4,5(loại)
c: (x-2)^3=64
=>(x-2)^3=4^3
=>x-2=4
=>x=6(nhận)
LA
0
DN
3
24 tháng 9 2019
a, \(\left|x\right|=-1,2\)
\(\Rightarrow x\in\varnothing\)
b, \(\left|x\right|+1,5=3,7\)
\(\left|x\right|=3,7-1,5\)
\(\left|x\right|=2,2\)
\(\Rightarrow x\in\left\{-2,2;2,2\right\}\)
c, \(\left|x+\frac{1}{3}\right|-4=-1\)
\(\left|x+\frac{1}{3}\right|=-1+4\)
\(\left|x+\frac{1}{3}\right|=3\)
\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{3}=3\\x+\frac{1}{3}=-3\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=3-\frac{1}{3}\\x=-3-\frac{1}{3}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{8}{3}\\x=-\frac{10}{3}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{8}{3};-\frac{10}{3}\right\}\)
DH
24 tháng 9 2019
Câu 1 :
\(\left|x\right|=-1,2\)
\(\Rightarrow x\in\left\{\varnothing\right\}\)
Câu 2 :
\(\left|x\right|+1,5=3,7\)
\(\left|x\right|=2,2\)
\(\Rightarrow x=2,2\) hoặc \(x=-2,2\)
Câu 3 :
\(\left|x+\frac{1}{3}\right|-4=-1\)
\(\left|x+\frac{1}{3}\right|=3\)
TH 1:
\(x+\frac{1}{3}=3\)
\(x=\frac{8}{3}\)
TH 2:
\(x+\frac{1}{3}=-3\)
\(x=-\frac{10}{3}\)
Vậy \(x=\frac{8}{3}\) và \(x=-\frac{10}{3}\)
10 tháng 7 2019
\(\left(x-1,2\right)^2=4\)
⇔\(x^2-2.x.1,2+1,2^2=4\)
⇔\(x^2-2,4x+1,44=4\)
⇔\(x^2-2,4x=4-1,44\)
⇔\(x\left(x-2,4\right)=2,56\)
⇔\(x=2,56\) hoặc \(x-2,4=2,56\)
⇔\(x=2,56\) hoặc \(x=4,96\)
11 tháng 7 2019
a) \(\left(x-1,2\right)^2=4=2^2\)
\(\Leftrightarrow x-1,2=4\)
\(\Leftrightarrow x=5,2\)
b) \(\left(x+1\right)^3=-125=\left(-5\right)^3\)
\(\Leftrightarrow x+1=-5\)
\(\Leftrightarrow x=-6\)
c) \(\left(x+1,5\right)^8+\left(2,7-y\right)^{10}=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x+1,5=0\\2,7-y=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-1,5\\y=2,7\end{matrix}\right.\)
3 tháng 6 2021
Giải:
a) \(\left(9\dfrac{4}{9}+5\dfrac{2}{3}\right)-5\dfrac{1}{2}\)
\(=\left(\dfrac{85}{9}+\dfrac{17}{3}\right)-\dfrac{11}{2}\)
\(=\dfrac{136}{9}-\dfrac{11}{2}\)
\(=\dfrac{173}{18}\)
b) \(\dfrac{13}{9}.\dfrac{15}{4}-\dfrac{13}{9}.\dfrac{7}{4}-\dfrac{13}{9}.\dfrac{5}{4}\)
\(=\dfrac{13}{9}.\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)\)
\(=\dfrac{13}{9}.\dfrac{3}{4}\)
\(=\dfrac{13}{12}\)
c) \(\dfrac{2}{3}+\dfrac{5}{8}-\dfrac{-1}{3}+0,375\)
\(=\left(\dfrac{2}{3}-\dfrac{-1}{3}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=1+1\)
\(=2\)
d) \(75\%-3\dfrac{1}{2}+1,5:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{3}{2}:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{21}{20}\)
\(=\dfrac{53}{10}\)
e) \(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-47}{60}:\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-2}{5}\)
\(=1\)
a) \(\frac{9}{4}-1,2+\frac{1}{4}=\frac{9}{4}+\frac{1}{4}-1,2=\frac{5}{2}-\frac{6}{5}=\frac{25-12}{10}=\frac{13}{10}\)
b) \(\frac{1}{3}+1,5-\frac{1}{4}=\frac{1}{3}+\frac{3}{2}-\frac{1}{4}=\frac{4+18-3}{12}=\frac{19}{12}\)