x-1=4x-8
giúp
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
5 tháng 11 2021
\(=x^2+6x+9-17=\left(x+3\right)^2-17=\left(x+3-\sqrt{17}\right)\left(x+3+\sqrt{17}\right)\)
13 tháng 11 2021
\(x\left(x-2\right)+x-2=0\\ \Leftrightarrow x\left(x-2\right)+\left(x-2\right)=0\\ \Leftrightarrow\left(x-2\right)\left(x+1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)
\(x^2-2x+1=9\\ \Leftrightarrow\left(x-1\right)^2=9\\ \Leftrightarrow\left[{}\begin{matrix}x-1=-3\\x-1=3\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
\(7x^2=2x\\ \Leftrightarrow7x^2-2x=0\\ \Leftrightarrow x\left(7x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\7x-2=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{2}{7}\end{matrix}\right.\)
\(x^2-6x=8\\ \Leftrightarrow x^2-6x-8=0\\ \left(x^2-6x+9\right)-17=0\\ \Leftrightarrow\left(x-3\right)^2-\sqrt{17^2}=0\\ \Leftrightarrow\left(x-3-\sqrt{17}\right)\left(x-3+\sqrt{17}\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-3-\sqrt{17}=0\\x-3+\sqrt{17}=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=3+\sqrt{17}\\x=3-\sqrt{17}\end{matrix}\right.\)
N
1
LA
1
15 tháng 7 2021
Ta có: \(3x^2-x+2\)
\(=3\left(x^2-\dfrac{1}{3}x+\dfrac{2}{3}\right)\)
\(=3\left(x^2-2\cdot x\cdot\dfrac{1}{6}+\dfrac{1}{36}+\dfrac{23}{36}\right)\)
\(=3\left(x-\dfrac{1}{6}\right)^2+\dfrac{23}{12}\ge\dfrac{23}{12}>0\forall x\)(đpcm)
NH
3
NA
20 tháng 1 2022
\(\Rightarrow a^2-1⋮8\\ \Rightarrow a^2⋮9\\ \Rightarrow a=\pm3\)
NA
3
20 tháng 6 2021
Tham khảo:
Nguồn:Vietjack
I think that the best leisure activity for teenagers is playing sports. Firstly, they can find friends who have the same interests. Secondly, physical activities are a good way to relieve stress and reduce depression. Moreover, sports can help develop teamwork and leadership skills that may be very necessary for their future jobs. Their parents should give advice on choosing a suitable leisure activity; however, teenagers themselves will make the final decision
x - 1 = 4x - 8
<=> 3x = 7
<=> x = 7/3
Vậy...
\(x-1=4x-8\)
\(\Rightarrow-1+8=4x-x\)
\(\Rightarrow7=3x\)
\(\Rightarrow x=\frac{7}{3}\)