4 Help meeeee.
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a) \(\left(3x-1\right)^6=\left(3x-1\right)^4\)
\(\Rightarrow\left[{}\begin{matrix}3x-1=0\\3x-1=1\\3x-1=-1\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=\dfrac{2}{3}\\x=0\end{matrix}\right.\)
b) Áp dụng t/c dtsbn:
\(\dfrac{a+b-c}{c}=\dfrac{a-b+c}{b}=\dfrac{-a+b+c}{a}=\dfrac{a+b+c}{a+b+c}=1\)
\(\Rightarrow\left\{{}\begin{matrix}a+b-c=c\\a-b+c=b\\-a+b+c=a\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}a+b=2c\\a+c=2b\\b+c=2a\end{matrix}\right.\)
\(\Rightarrow M=\dfrac{\left(a+b\right)\left(b+c\right)\left(c+a\right)}{abc}=\dfrac{2a.2b.2c}{abc}=8\)
1 went
2 have never been
3 haven't seen
4 saw
5 have they been
6 got
7 have already done
1. I went to the new Mexican restaurant yesterday.
2. I have never been there. Did you like it?
3. I have not seen Ann for a very long time.
4. Really? I saw her yesterday at the gym.
5. How long have they been married?
6. Only a year. They got married last June.
7. No, you don't have to. I have already done it.
Ta có: \(\frac{x}{1,75}\)=\(\frac{y}{0,75}\) và x-y = 4
⇒ \(\frac{x}{1,75}\)=\(\frac{y}{0,75}\)=\(\frac{x-y}{1,75-0,75}\)=\(\frac{4}{1}\)=4
⇒\(\frac{x}{1,75}\)=4 ⇔ x = 4 . 1,75 = 7
⇒\(\frac{y}{0,75}\)= 4 ⇔ y = 4 . 0,75 = 3
Vậy x = 7 ; y = 3
\(\left(x-\dfrac{1}{5}\right)^2=\dfrac{4}{25}\Leftrightarrow\left(x-\dfrac{1}{5}\right)^2=\left(\dfrac{2}{5}\right)^2\)
\(\Leftrightarrow x-\dfrac{1}{5}=\dfrac{2}{5}\Leftrightarrow x=\dfrac{3}{5}\)
pt \(\Leftrightarrow\)\(\left[{}\begin{matrix}x-\dfrac{1}{5}=\dfrac{2}{5}\\x-\dfrac{1}{5}=-\dfrac{2}{5}\end{matrix}\right.\)\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=\dfrac{3}{5}\\x=-\dfrac{1}{5}\end{matrix}\right.\)
Bài 4:
\(M+\left(5x^2-2y^3\right)=10x^2+4y^3\)
\(=>M=\left(10x^2+4y^3\right)-\left(5x^2-2y^3\right)\)
\(M=10x^2+4y^3-5x^2+2y^3\)
\(M=\left(10x^2-5x^2\right)+\left(4y^3+2y^3\right)\)
\(M=5x^2+6y^3\)
Vì \(M+N=8x^2-3y^2\)
\(=>N=\left(8x^2-3y^2\right)-\left(5x^2+6y^3\right)\)
\(N=8x^2-3y^2-5x^2-6y^3\)
\(N=\left(8x^2-5x^2\right)-3y^2-6y^3\)
\(=>N=3x^2-3y^2-6y^3\)
lần sau cái đề bài nó ngắn thì viết ra, đọc thế này mỏi cổ lắm, bộ ko type ra đc à @Lucy Châu