Rút gọn biểu thức
A=\(\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\)
B=\(\sqrt{x+\sqrt{2x-1}}+\sqrt{x-\sqrt{2x-1}}\)
Rút gọn biểu thức : A=\(\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\)
ĐKXĐ: \(x\ge2\)
\(A=\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\)
\(=\sqrt{x-2+2.\sqrt{x-2}.\sqrt{2}+2}+\sqrt{x-2-2.\sqrt{x-2}.\sqrt{2}+2}\)
\(=\sqrt{\left(\sqrt{x-2}+\sqrt{2}\right)^2}+\sqrt{\left(\sqrt{x-2}-\sqrt{2}\right)^2}\)
\(=\left|\sqrt{x-2}+\sqrt{2}\right|+\left|\sqrt{x-2}-\sqrt{2}\right|=\sqrt{x-2}+\sqrt{2}+\left|\sqrt{x-2}-\sqrt{2}\right|\)
Xét \(x\ge4\Rightarrow\sqrt{x-2}\ge\sqrt{2}\)
\(\Rightarrow A=\sqrt{x-2}+\sqrt{2}+\sqrt{x-2}-\sqrt{2}=2\sqrt{x-2}\)
Xét \(0\le x< 4\Rightarrow\sqrt{x-2}< \sqrt{2}\)
\(\Rightarrow A=\sqrt{x-2}+\sqrt{2}-\sqrt{x-2}+\sqrt{2}=2\sqrt{2}\)
Rút gọn biểu thức:
\(A=\frac{\sqrt{x+2\sqrt{x-1}+\sqrt{x-2\sqrt{x-1}}}}{\sqrt{x+\sqrt{2x-1}+\sqrt{x-\sqrt{2x-1}}}}.\sqrt{2x-1}\)
Rút gọn biểu thức sau với x \(\ge\) 0
a) \(3\sqrt{2x}-4\sqrt{2x}+8-2\sqrt{x}\)
b) \(3\sqrt{2x}-\sqrt{72x}+3\sqrt{18x}+18\)
a) \(3\sqrt{2x}-4\sqrt{2x}+8-2\sqrt{x}\)
\(=-\left(4\sqrt{2x}-3\sqrt{2x}\right)+8-2\sqrt{x}\)
\(=-\sqrt{2x}-2\sqrt{x}+8\)
b) \(3\sqrt{2x}-\sqrt{72x}+3\sqrt{18x}+18\)
\(=3\sqrt{2x}-6\sqrt{2x}+3\cdot3\sqrt{2x}+18\)
\(=3\sqrt{2x}-6\sqrt{2x}+9\sqrt{2x}+18\)
\(=\left(3+9-6\right)\sqrt{2x}+18\)
\(=6\sqrt{2x}+18\)
Rút gọn biểu thức :
a) \(A=\left(a-1\right)\sqrt{\frac{a}{a-1}}+\sqrt{a\left(a-1\right)}-a\sqrt{\frac{a-1}{a}}\)
b) \(B=\frac{1-\sqrt{x-1}}{\sqrt{x}+2\sqrt{x-1}}-\frac{1+\sqrt{x-1}}{\sqrt{x}-2\sqrt{x-1}}\)
c)\(C=\frac{\sqrt{x-\sqrt{2x-1}}+\sqrt{x+\sqrt{2x-1}}}{\sqrt{x+\sqrt{2x-1}}.\sqrt{x-\sqrt{2x-1}}}.\sqrt{2x-1}\)
d) D=\(\sqrt{\sqrt{a}-\sqrt{\frac{a^2-4}{a}}}-\sqrt{\sqrt{a}+\sqrt{\frac{a^2-4}{a}}}\)
\(A=\left(a-1\right)\sqrt{\frac{a}{a-1}}+\sqrt{a\left(a-1\right)}-a\sqrt{\frac{a-1}{a}}\)
\(A=\sqrt{\left(a-1\right)^2.\frac{a}{a-1}}+\sqrt{a\left(a-1\right)}-\sqrt{a^2.\frac{a-1}{a}}\)
\(A=\sqrt{\left(a-1\right)a}+\sqrt{a\left(a-1\right)}-\sqrt{a\left(a-1\right)}\)
\(A=\sqrt{a\left(a-1\right)}\)
Bài 1: Rút gọn biểu thức: \(A=\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\)
\(A=\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}\)
\(=\sqrt{x-2+2\sqrt{x-2}\sqrt{2}+2}+\sqrt{x-2-2\sqrt{x-2}\sqrt{2}+2}\)
\(=\sqrt{\left(\sqrt{x-2}+\sqrt{2}\right)^2}+\sqrt{\left(\sqrt{x-2}-\sqrt{2}\right)^2}\)
\(=\left|\sqrt{x-2}+\sqrt{2}\right|+\left|\sqrt{x-2}-\sqrt{2}\right|\)
\(\text{Với }\sqrt{x-2}\ge\sqrt{2}\text{ thì : }A=\sqrt{x-2}+\sqrt{2}+\sqrt{x-2}-\sqrt{2}=2\sqrt{x-2}\)
\(\text{Với }\sqrt{x-2}\le\sqrt{2}\text{ thì : }A=\sqrt{x-2}+\sqrt{2}+\sqrt{2}-\sqrt{x-2}=2\sqrt{2}\)
Rút gọn biểu thức:
1) \(\sqrt{9-4\sqrt{5}}+\sqrt{\left(25+1\right)^2}\)
2) \(\dfrac{x^2-5}{x+\sqrt{5}}\)
3) \(\dfrac{\sqrt{x^2-2x+1}}{x-1}\)
4) \(\sqrt{4+\sqrt{7}}-\sqrt{4-\sqrt{7}}\)
1)\(=\sqrt{\left(\sqrt{5}-2\right)^2}+\sqrt{26^2}=\sqrt{5}-2+26=24-\sqrt{5}\)
2) \(=\dfrac{\left(x-\sqrt{5}\right)\left(x+\sqrt{5}\right)}{x+\sqrt{5}}=x-\sqrt{5}\)
3) \(=\dfrac{\sqrt{\left(x-1\right)^2}}{x-1}=\dfrac{\left|x-1\right|}{x-1}\)\(=\left[{}\begin{matrix}1\left(x>1\right)\\-1\left(x< 1\right)\end{matrix}\right.\)
4) \(=\sqrt{\left(\sqrt{\dfrac{7}{2}}+\sqrt{\dfrac{1}{2}}\right)^2}-\sqrt{\left(\sqrt{\dfrac{7}{2}}-\sqrt{\dfrac{1}{2}}\right)^2}=\sqrt{\dfrac{7}{2}}+\sqrt{\dfrac{1}{2}}-\sqrt{\dfrac{7}{2}}+\sqrt{\dfrac{1}{2}}=2\sqrt{\dfrac{1}{2}}=\sqrt{2}\)
2. \(\dfrac{x^2-5}{x+\sqrt{5}}=\dfrac{x^2-\left(\sqrt{5}\right)^2}{x+\sqrt{5}}=\dfrac{\left(x-\sqrt{5}\right)\left(x+\sqrt{5}\right)}{x+\sqrt{5}}=x-\sqrt{5}\)
3. \(\dfrac{\sqrt{x^2-2x+1}}{x-1}=\dfrac{\sqrt{x^2-2.x.1+1^2}}{x-1}=\dfrac{\sqrt{\left(x-1\right)^2}}{x-1}=\dfrac{|x-1|}{x-1}=\left[{}\begin{matrix}x-1>0\left(x>1\right)\\x-1< 0\left(x< 1\right)\end{matrix}\right.=\left[{}\begin{matrix}=1\\=\dfrac{x+1}{x-1}\end{matrix}\right.\)
Rút gọn biểu thức:
\(A=\frac{\sqrt{x+2\sqrt{x-1}+\sqrt{x-2\sqrt{x-1}}}}{\sqrt{x+\sqrt{2x-1}+\sqrt{x-\sqrt{2x-1}}}}.\sqrt{2x-1}\)
Giúp với.
Cho A = \(\dfrac{\sqrt{x}}{\sqrt{x}+2}+\dfrac{\sqrt{x}+2}{\sqrt{x}-2}+\dfrac{2x+8}{2x-4}\) và B = \(\dfrac{2}{\sqrt{x}-6}\) với \(x\ge0;x\ne4;x\ne36\)
a) Rút gọn các biểu thức A
b) Tìm GTNN của biểu thức P = A : B
Bạn xem lại xem đã biết biểu thức đúng chưa vậy?
\(\frac{\sqrt{x+2\sqrt{x-1}}+\sqrt{x-2\sqrt{x-1}}}{\sqrt{x+\sqrt{2x-1}}-\sqrt{x-\sqrt{2x-1}}}\)
rút gọn biểu thức
\(\frac{A}{\sqrt{2}}\)=\(\frac{\sqrt{x-1+2\sqrt{x-1}+1}+\sqrt{x-1-2\sqrt{x-1}+1}}{\sqrt{2x-1+2\sqrt{2x-1}+1}-\sqrt{2x-1-2\sqrt{2x-1}+1}}\) (DK \(x\ge1\)
\(=\frac{\sqrt{x-1}+1+\left|\sqrt{x-1}-1\right|}{\sqrt{2x-1}+1-\left|\sqrt{2x-1}-1\right|}\)
vs \(x\ge2\) \(\frac{\sqrt{x-1}+1+\sqrt{x-1}-1}{\sqrt{2x-1}+1-\sqrt{2x-1}+1}=\frac{2\sqrt{x-1}}{2}=\sqrt{x-1}\) \(\Rightarrow A=\sqrt{2x-2}\)
vs \(1\le x< 2\) \(\frac{\sqrt{x-1}+1+1-\sqrt{x-1}}{\sqrt{2x-1}+1-1+\sqrt{2x-1}}=\frac{1}{\sqrt{2x-1}}\) \(\Rightarrow A=\frac{\sqrt{2}}{\sqrt{2x-1}}\)
\(\sqrt{2X-1}\ge1\Leftrightarrow X\ge1\)NEN SUY RA THEO CACH LAM CUA TO
THOI U AM BUSY SEE YOU AGAIN
làm zì mà dài vậy \(\sqrt{x+2\sqrt{x-1}}=\sqrt{x-1+2\sqrt{x-1}+1}=\sqrt{\left(\sqrt{x-1}-1\right)^2}\)