ta có : \(x^2-4x+5=x^2-2.2x+2^2+1=\left(x-2\right)^2+1\ge1\left(\forall x\right)\)
\(=>\sqrt{x^2-4x+5}\ge1\)
dấu'=' xảy ra<=>x=2
Giải phương trình:
*\(\sqrt{x^2-4x+5}+\sqrt{x^2-4x+8}+\sqrt{x^2-4x+9}=3+\sqrt{5}\)
*\(\sqrt{x+3-4\sqrt{x-1}+\sqrt{x+8+6\sqrt{x-1}=5}}\)
Bài 1: CMR với a, b không âm, ta có:
a) \(\dfrac{a+b}{2}>=\sqrt{ab}\)
Giải pt:
\(\sqrt{-x^2+4x-2}+\sqrt{-2x^2+8x-5}=\sqrt{2}+\sqrt{3}\)
Giả phương trình:
a/ \(\sqrt{x^2-4x+5}+\sqrt{x^2-4x+8}+\sqrt{x^2-4x+9}=3+\sqrt{5}\)
b/ \(\sqrt{2-x^2+2x}+\sqrt{-x^2-6x-8}=1+\sqrt{3}\)
Cho \(x=\frac{1}{2}\sqrt{\frac{\sqrt{2}-1}{\sqrt{2}+1}}\). Tính:
\(M=\left(4x^5+4x^4-x^3+1\right)^{19}+\left(\sqrt{4x^5+4x^4-5x^3+5x+3}\right)^3+\left(\frac{1-\sqrt{2}}{\sqrt{2x^2+2x}}\right)^{2016}\)
tìm x:
\(\sqrt{x^2+x+1}=1\)
\(\sqrt{x^2+1}=-3\)
\(\sqrt{x^2-10x+25}=7-2x\)
\(\sqrt{2x+5}=5\)
\(\sqrt{x^2-4x+4}-2x+5=0\)
Bài 2
a) A= \(\sqrt{\left(1-\sqrt{2}\right)^2}+\sqrt{\left(-2\right)^6}-\sqrt{\left(1+\sqrt{2}\right)^2}\)
b) B= \(\sqrt{7+2\sqrt{6}}+\sqrt{7-2\sqrt{6}}\)
c) C= \(\sqrt{7-4\sqrt{3}}\)
d) D= \(2\sqrt{7+4\sqrt{3}}-\sqrt{13-4\sqrt{3}}\)
e) E= \(\frac{1}{1+\sqrt{3}}+\frac{1}{\sqrt{3}+\sqrt{5}}+...+\frac{1}{\sqrt{79}+\sqrt{81}}\)
Bài 4:
a) \(\sqrt{x-1}=2\)
b) \(\sqrt{x^2-3x+2}=\sqrt{2}\)
c) \(\sqrt{4x+1}=x+1\)
d) \(\sqrt{x+2\sqrt{x-1}}-\sqrt{x-2\sqrt{x-1}}=2\)
e) \(\sqrt{x^2-4x+5}+\sqrt{x^2-4x+8}+\sqrt{x^2-4x+9}=3+\sqrt{5}\)
f)
\(\sqrt{4x^2+9x+5}=\sqrt{x^2-1}+\sqrt{2x^2+x-1}\)
\(\sqrt{7-\frac{1}{5}x}\) 2) \(\sqrt{\frac{4}{3}+2x}\)
\(\sqrt{\frac{2}{x^2+\frac{1}{2}}}\) 4) \(\sqrt{\frac{-2}{x^2+\frac{1}{3}}}\)
\(\sqrt{\frac{-5}{x^2+4x}}\) 6) \(\sqrt{\frac{5}{x^2+4x}}\)
\(\sqrt{\frac{2}{x^2+3x-4}}\) 8)\(\sqrt{\frac{2}{3x^2+5x-8}}\)
\(\sqrt{\frac{-6}{x^2-25}}\) 10)\(\sqrt{\frac{-7}{4x^2-9}}\)
\(\sqrt{\frac{2}{4x^2+x+3}}\) Gỉai phương trình
Giúp mk vs các bn mk bí rồi.
Rút gọn:
a,\(\sqrt{4x^2-4x+1}-2x+3\) (x≥\(\frac{1}{2}\))
b,B=\(\sqrt{\frac{3\sqrt{5}+1}{2\sqrt{5}-3}}\left(\sqrt{10}-\sqrt{2}\right)\)
