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VM
17 tháng 12 2019
a) \(5\frac{3}{7}+\frac{7}{29}-0,7-\frac{3}{17}+\frac{22}{19}-2,3\)
\(=\frac{38}{7}+\frac{7}{29}-\frac{7}{10}-\frac{3}{17}+\frac{22}{19}-\frac{23}{10}\)
\(=\left(-\frac{7}{10}-\frac{23}{10}\right)+\frac{38}{7}+\frac{7}{29}-\frac{3}{17}+\frac{22}{19}\)
\(=\left(-3\right)+\frac{38}{7}+\frac{7}{29}-\frac{3}{17}+\frac{22}{19}\)
\(=\frac{17}{7}+\frac{7}{29}-\frac{3}{17}+\frac{22}{19}\)
\(=\frac{8605}{3451}+\frac{22}{19}\)
\(\approx4.\)
d) \(\sqrt{0,36}-\sqrt{0,81}+\sqrt{0,49}\)
\(=0,6-0,9+0,7\)
\(=\left(-0,3\right)+0,7\)
\(=0,4.\)
Chúc bạn học tốt!
QD
19 tháng 6 2019
a)\(\left(\frac{1}{5}\right)^{3x-1}=\frac{1}{25}\)
\(\Leftrightarrow\left(\frac{1}{5}\right)^{3x-1}=\left(\frac{1}{5}\right)^2\)
<=> 3x-1=2
<=> 3x=3
<=> x=1
c) \(\left(\frac{2}{3}\right)^{1-x}=\left(\frac{2}{3}\right)^3\)
<=> 1-x=3
<=>x=-2
d) (0,7)3x+1=(0,7)3
<=> 3x+1=3
<=> 3x=2
<=> x=2/3
LT
25 tháng 11 2019
Bai 1
a) \(\sqrt{0,36}+\sqrt{0,49}=0,6+0,7=1,3\)
b) \(\sqrt{\frac{4}{9}}-\sqrt{\frac{25}{36}}=\frac{2}{3}-\frac{5}{6}\)
=\(-\frac{1}{6}\)
Bài 2
a)\(x^2=81\Rightarrow\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)
b) \(\left(x-1\right)^2=\frac{9}{16}\)
\(\Rightarrow\left[{}\begin{matrix}x-1=\frac{3}{4}\\x-1=\frac{-3}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{7}{4}\\x=\frac{1}{4}\end{matrix}\right.\)
c) \(x-2\sqrt{x}=0\Rightarrow\sqrt{x}\left(\sqrt{x}-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}=0\\\sqrt{x}-2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)
d) \(x=\sqrt{x}\Rightarrow x-\sqrt{x}=0\Rightarrow\sqrt{x}\left(\sqrt{x}-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}\sqrt{x}=0\\\sqrt{x}-1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
10 tháng 7 2022
a: \(A=-\left|3x-1\right|+0.7< =0,7\)
Dấu '=' xảy ra khi x=1/3
b: |x+0,3|+0,5>=0,5
=>B<=1/0,5=2
Dấu '=' xảy ra khi x=-0,3
c: \(C=0.5\cdot\left|0.3x-2\right|+0.7>=0.7\)
Dấu '=' xảy ra khi x=2/0,3=20/3
21 tháng 10 2016
a,15^8*9^7/27^7*25^4
=3^8*5^8*3^14/3^21*5^8
=3^22*5^8/3^21*5^8
=3
b,9^3/(3^4-3^3)^2
=3^6/3^8-3^6
=3^6/3^6*(3^2-1)
=3^6/3^6*8
=1/8
c,(1/2-2/3+3/4-2/5):x=11/30
=> 11/60:x=11/30
=> x=11/60:11/30
=> x=1/2
d,-3/4*x+0,7*x=1,25:1/8
=> x*(-3/4+0,7)=10
=> x*(-1/20)=10
=> x=10:(-1/20)=200
Mình làm tắt lắm mong bạn thông cảm.
S
1
27 tháng 10 2016
Ta có:
\(\sqrt{0,49}+\sqrt{\frac{25}{36}}=\sqrt{0,7^2}+\sqrt{\left(\frac{5}{6}\right)^2}=0,7+\frac{5}{6}=\frac{23}{15}\)
27 tháng 11 2022
a: \(=\left(\dfrac{1}{4}+\dfrac{3}{4}\right)\cdot\dfrac{18}{5}-\dfrac{6}{5}:\dfrac{-9}{5}+4\)
\(=\dfrac{18}{5}-\dfrac{6}{5}\cdot\dfrac{-5}{9}+4\)
\(=\dfrac{18}{5}+\dfrac{2}{3}+4\)
\(=\dfrac{124}{15}\)
b: \(=\dfrac{9}{25}\cdot\left(\dfrac{3}{5}-\dfrac{1}{5}+\dfrac{1}{2}\right)-\dfrac{3}{8}:\dfrac{9}{8}\)
\(=\dfrac{9}{25}\cdot\dfrac{4}{10}-\dfrac{1}{3}\)
\(=-\dfrac{71}{375}\)
c: \(=\dfrac{7}{10}:\dfrac{4}{5}+\dfrac{2}{9}:\dfrac{5}{9}+\dfrac{1}{8}\)
\(=\dfrac{7}{10}\cdot\dfrac{5}{4}+\dfrac{2}{5}+\dfrac{1}{8}\)
=1+2/5
=7/5
d: \(=\dfrac{3}{7}\left(19+\dfrac{1}{3}-33-\dfrac{1}{3}\right)-\dfrac{2}{7}=\dfrac{3}{7}\cdot\left(-14\right)-\dfrac{2}{7}=-6-\dfrac{2}{7}=\dfrac{-44}{7}\)
e: \(=\dfrac{2^{12}\cdot3^{10}+2^{12}\cdot3^{10}\cdot5}{-2^{11}\cdot3^{11}-2^{12}\cdot3^{12}}\)
\(=\dfrac{2^{12}\cdot3^{10}\cdot6}{-2^{11}\cdot3^{11}\left(1+2\cdot3\right)}=-\dfrac{2^{13}\cdot3^{11}}{2^{11}\cdot3^{11}\cdot7}=\dfrac{-4}{7}\)
\(0,7^2x=0,49^3\\ \Leftrightarrow0,49x=0,49^3\\ \Rightarrow x=0,49^3:0,49=0,49^2\)
Đs...