3^x+1.3^x=27
2^x+2+2^x=80
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\(1,\sqrt{3}x-3=\sqrt{27}\)
\(\Leftrightarrow\sqrt{3}x-3=3\sqrt{3}\)
\(\Leftrightarrow\sqrt{3}\left(x-\sqrt{3}\right)=3\sqrt{3}\)
\(\Leftrightarrow x-\sqrt{3}=3\)
\(\Leftrightarrow x=3+\sqrt{3}\)
\(2,\sqrt{2}x-\sqrt{28}=\sqrt{32}\)
\(\Leftrightarrow\sqrt{2}x-2\sqrt{7}=4\sqrt{2}\)
\(\Leftrightarrow\sqrt{2}x=4\sqrt{2}+2\sqrt{7}\)
\(\Leftrightarrow x=\dfrac{\sqrt{2^2}\left(2\sqrt{2}+\sqrt{7}\right)}{\sqrt{2}}\)
\(\Leftrightarrow x=\sqrt{2}\left(2\sqrt{2}+\sqrt{7}\right)\)
\(\Leftrightarrow x=4+\sqrt{14}\)
\(3,\sqrt{6}x-2\sqrt{6}=\sqrt{54}\)
\(\Leftrightarrow\sqrt{6}\left(x-2\right)=3\sqrt{6}\)
\(\Leftrightarrow x-2=3\)
\(\Leftrightarrow x=5\)
\(4,\sqrt{3}x-\sqrt{2}x=\sqrt{3}+\sqrt{2}\)
\(\Leftrightarrow\left(\sqrt{3}-\sqrt{2}\right)x=\sqrt{3}+\sqrt{2}\)
\(\Leftrightarrow x=\dfrac{\sqrt{3}+\sqrt{2}}{\sqrt{3}-\sqrt{2}}\)
a) \(\left(x+1\right)\left(x+2\right)=272\)
\(\Rightarrow x^2+3x+2=272\)
\(\Rightarrow x^2+3x-270=0\)
\(\Rightarrow x^2+18x-15x-270=0\)
\(\Rightarrow x\left(x+18\right)-15\left(x+18\right)=0\)
\(\Rightarrow\left(x+18\right)\left(x-15\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+18=0\\x-15=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-18\\x=15\end{matrix}\right.\)
d) \(\left(x+4\right)\left(x+5\right)=552\)
\(\Rightarrow x^2+9x+20=552\)
\(\Rightarrow x^2+9x-532=0\)
\(\Rightarrow x^2+28x-19x-532=0\)
\(\Rightarrow x\left(x+28\right)-19\left(x+28\right)=0\)
\(\Rightarrow\left(x+28\right)\left(x-19\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+28=0\\x-19=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-28\\x=19\end{matrix}\right.\)
a,504:[16-3.x]=72
16-3.x=504:72
16-3.x=7
3.x =16-7
3.x =9
\(\Rightarrow x=3\)
b,272-[4.x+15] = 45
4.x+15 = 272-45
4.x+15 = 227
4.x = 227-15
4.x = 212
x = 212:4
\(\Rightarrow x=53\)
c,425-x:8 =91
x:8 =425-91
x:8 =334
x =334x8
\(\Rightarrow x=2672\)
d, 293-8.27+x.25=80
293-216 +x.25=80
77+x.25 =80
x.25 =3
\(\Rightarrow x=\frac{3}{25}\)
x = 3
x = 53
x = 2672
x = 3 / 25
ai thấy đúng thì ủng hộ mk nha
\(\dfrac{2^2}{1.3}.\dfrac{3^2}{2.4}.\dfrac{4^2}{3.5}.....\dfrac{99^2}{98.100}\)
\(=\dfrac{2.2.3.3.4.4.....99.99}{1.3.2.4.3.5.....98.100}\)
\(=\dfrac{2.3.4.....99}{1.2.3.4.....98}.\dfrac{2.3.4.....99}{3.4.5.....100}\)
\(=\dfrac{99}{98}\cdot\dfrac{2}{100}\)
\(=\dfrac{99}{4900}\)
2.(x-3)+3x+0.5=\(\dfrac{3}{4}\)
4x+2+4x=272
(1,2-5x).(2\(\dfrac{1}{8}\) +1/2 x)=0
GIÚP MÌNH VỚI !!!!
\(2\left(x-3\right)+3x+0,5=\dfrac{3}{4}\\ \Leftrightarrow2x-6+3x+\dfrac{1}{2}=\dfrac{3}{4}\\ \Leftrightarrow x\left(2+3\right)=\dfrac{3}{4}-\dfrac{1}{2}+6\\ \Leftrightarrow5x=\dfrac{25}{4}\\ \Leftrightarrow x=\dfrac{25}{4}:5=\dfrac{5}{4}\\ ---\\ 4^{x+2}+4^x=272\\ \Leftrightarrow4^x\left(4^2+1\right)=272\\ \Leftrightarrow4^x.17=272\\ \Leftrightarrow4^x=\dfrac{272}{17}=16=4^2\\ Vậy:x=2\\ ----\\ \left(1,2-5x\right)\left(2\dfrac{1}{8}+\dfrac{1}{2}x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}1,2-5x=0\\2,125+0,5x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=1,2\\0,5x=-2,125\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1,2}{5}=0,24\\x=\dfrac{-2,125}{0,5}=-4,25\end{matrix}\right.\)
a) \(2\left(x-3\right)+3x+0,5=\dfrac{3}{4}\)
\(\Rightarrow2x-6+3x+\dfrac{1}{2}=\dfrac{3}{4}\)
\(\Rightarrow5x-6=\dfrac{3}{4}-\dfrac{1}{2}\)
\(\Rightarrow5x-6=\dfrac{1}{4}\)
\(\Rightarrow5x=\dfrac{1}{4}+6\)
\(\Rightarrow5x=\dfrac{25}{4}\)
\(\Rightarrow x=\dfrac{25}{4}:5\)
\(\Rightarrow x=\dfrac{5}{4}\)
b) \(4^{x+2}+4^x=272\)
\(\Rightarrow4^x\cdot4^2+4^x\cdot1=272\)
\(\Rightarrow4^x\cdot\left(16+1\right)=272\)
\(\Rightarrow4^x\cdot17=272\)
\(\Rightarrow4^x=16\)
\(\Rightarrow4^x=4^2\)
\(\Rightarrow x=2\)
c) \(\left(1,2-5x\right)\left(2\dfrac{1}{8}+\dfrac{1}{2}x\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}1,2-5x=0\\\dfrac{15}{8}+\dfrac{1}{2}x=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}5x=1,2\\\dfrac{1}{2}x=-\dfrac{15}{8}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1,2}{5}\\x=-\dfrac{15}{8}:\dfrac{1}{2}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{6}{25}\\x=-\dfrac{15}{4}\end{matrix}\right.\)
Bài làm
3x + 1.3x = 27
3x + 3x = 27
2.3x = 27
3x = 27 : 2
3x = \(\frac{27}{2}\)
x = \(\frac{27}{2}:3\)
x = \(\frac{27}{2}.\frac{1}{3}\)
x = \(\frac{9}{2}\)
Vậy x = \(\frac{9}{2}\)
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Bài làm
~ Mik làm nhầm rồi nha, đừng ai k đúng ~
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