giải các phương trình sau ( mình đang cần gấp cảm ơn )
1) x+\(\sqrt{4-x^2}\)= 2+2x.\(\sqrt{4-x^2}\)
2) \(\sqrt{2x^2+11x+19}\)+\(\sqrt{2x^2+5x+1}\)=3.( x+1)
3) \(\sqrt{4x^2+5x+1}\)- 2\(\sqrt{x^2-x+1}\)=9x-3
4) \(\sqrt{2x^2+7x+10}\)+\(\sqrt{2x^2+x+4}\)= 3( x+1)
5) 2x2+5x-1=7.\(\sqrt{x^3-1}\)
6) 2x2+4 = 3\(\sqrt{x^3+1}\)
7) 10\(\sqrt{x^3+1}\)=...
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giải các phương trình sau ( mình đang cần gấp cảm ơn )
1) x+\(\sqrt{4-x^2}\)= 2+2x.\(\sqrt{4-x^2}\)
2) \(\sqrt{2x^2+11x+19}\)+\(\sqrt{2x^2+5x+1}\)=3.( x+1)
3) \(\sqrt{4x^2+5x+1}\)- 2\(\sqrt{x^2-x+1}\)=9x-3
4) \(\sqrt{2x^2+7x+10}\)+\(\sqrt{2x^2+x+4}\)= 3( x+1)
5) 2x2+5x-1=7.\(\sqrt{x^3-1}\)
6) 2x2+4 = 3\(\sqrt{x^3+1}\)
7) 10\(\sqrt{x^3+1}\)= 3x2+6
7.
ĐKXĐ: ...
\(\Leftrightarrow10\sqrt{\left(x+1\right)\left(x^2-x+1\right)}=3\left(x^2+2\right)\)
Đặt \(\left\{{}\begin{matrix}\sqrt{x^2-x+1}=a>0\\\sqrt{x+1}=b\ge0\end{matrix}\right.\)
\(\Rightarrow10ab=3\left(a^2+b^2\right)\)
\(\Leftrightarrow3a^2-10ab+3b^2=0\)
\(\Leftrightarrow\left(a-3b\right)\left(3b-a\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}a=3b\\3a=b\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\sqrt{x^2-x+1}=3\sqrt{x+1}\\3\sqrt{x^2-x+1}=\sqrt{x-1}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-x+1=9x+9\\9x^2-9x+9=x-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-10x-8=0\\9x^2-10x+10=0\end{matrix}\right.\) (casio)
6.
ĐKXĐ: ...
\(\Leftrightarrow2x^2+4=3\sqrt{\left(x+1\right)\left(x^2-x+1\right)}\)
Đặt \(\left\{{}\begin{matrix}\sqrt{x^2-x+1}=a>0\\\sqrt{x+1}=b\ge0\end{matrix}\right.\)
\(\Rightarrow2a^2+2b^2=3ab\)
\(\Leftrightarrow2a^2-3ab+2b^2=0\)
Phương trình vô nghiệm (vế phải là \(5\sqrt{x^3+1}\) sẽ hợp lý hơn)