Giai PT
\(\sqrt{4x-20}-3.\sqrt{\frac{x-5}{9}=2}\)
Giai các PT sau
a, \(x=\sqrt{2-x}.\sqrt{3-x}+\sqrt{3-x}.\sqrt{5-x}+\sqrt{2-x}.\sqrt{5-x}\)
b, \(\sqrt{5x^2+14x+9}-\sqrt{x^2-x-20}=5\sqrt{x+1}\)
c, \(\sqrt{4x+1}+\sqrt{2x^2+x+39}=10\)
Giai các PT sau
a, \(x=\sqrt{2-x}.\sqrt{3-x}+\sqrt{3-x}.\sqrt{5-x}+\sqrt{2-x}.\sqrt{5-x}\)
b, \(\sqrt{5x^2+14x+9}-\sqrt{x^2-x-20}=5\sqrt{x+1}\)
c, \(\sqrt{4x+1}+\sqrt{2x^2+x+39}=10\)
Giải PT
\(\sqrt{4x-20}-3\sqrt{\frac{x-5}{9}}=\sqrt{1-x}\)
\(\sqrt{4x+8}+2\sqrt{x+2}-\sqrt{9x+18}=1\)
\(\sqrt{3x^2-4x+3}=1-2x\)
\(\sqrt{16\left(x+1\right)}-\sqrt{9\left(x+1\right)}=4\)
Câu 1 :
Xét điều kiện:\(\hept{\begin{cases}x\ge5\\x\le1\end{cases}}\)(Vô lý)
Vậy pt vô nghiệm
Câu 2 :
\(2\sqrt{x+2}+2\sqrt{x+2}-3\sqrt{x+2}=1\)\(\Leftrightarrow\sqrt{x+2}=1\Leftrightarrow x=-1\)
Vậy x=-1
Câu 3 :
\(\sqrt{3x^2-4x+3}=1-2x\)\(\Leftrightarrow3x^2-4x+3=1+4x^2-4x\)
\(\Leftrightarrow x^2=2\Leftrightarrow x=\sqrt{2}\)
Câu 4 :
\(4\sqrt{x+1}-3\sqrt{x+1}=4\Leftrightarrow\sqrt{x+1}=4\)
\(\Leftrightarrow x=15\)
giai pt
\(\sqrt{\frac{4x+9}{28}}=7x^2+7x\)\(\sqrt{x-7}+\sqrt{5-x}=x^2-16x+66\)giai pt:
a) \(\sqrt{x^2-4x-12}=9-2x\)
b) \(\left(x+1\right)\sqrt[3]{15x^2-x-1}=x^2-1\)
c) \(\left(2x-2\right)\sqrt{2x-1}=6\left(x-1\right)\)
d) \(\frac{\sqrt{-x^2+4x-3}-1}{x-3}=2\)
e) \(\frac{5+\sqrt{x+1}}{x-2}=7\)
Đệ biết là có người làm câu c,d nên xin xí câu e :3
ĐK: \(\left\{{}\begin{matrix}x\ge-1\\x\ne2\end{matrix}\right.\)
\(PT\Leftrightarrow5+\sqrt{x+1}=7\left(x-2\right)\)
\(\Leftrightarrow\sqrt{x+1}=7x-19\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge\frac{19}{7}\\x+1=49x^2-266x+361\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x\ge\frac{19}{7}\\49x^2-267x+360=0\end{matrix}\right.\)
\(\Rightarrow x=3\left(tm\right)\)
a/ \(\Leftrightarrow\left\{{}\begin{matrix}9-2x\ge0\\x^2-4x-12=\left(9-2x\right)^2\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\le\frac{9}{2}\\3x^2-32x+93=0\end{matrix}\right.\)
Phương trình vô nghiệm
b/ \(\Leftrightarrow\left(x+1\right)\sqrt[3]{15x^2-x-1}-\left(x+1\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(\sqrt[3]{15x^2-x-1}-x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\Rightarrow x=-1\\\sqrt[3]{15x^2-x-1}-x+1=0\left(1\right)\end{matrix}\right.\)
\(\left(1\right)\Leftrightarrow\sqrt[3]{15x^2-x-1}=x-1\)
\(\Leftrightarrow15x^2-x-1=x^3-3x^2+3x-1\)
\(\Leftrightarrow x^3-18x^2+4x=0\)
\(\Leftrightarrow x\left(x^2-18x+4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=9\pm\sqrt{77}\\\end{matrix}\right.\)
c/ ĐKXĐ: \(x\ge\frac{1}{2}\)
\(\Leftrightarrow2\left(x-1\right)\sqrt{2x-1}-6\left(x-1\right)=0\)
\(\Leftrightarrow2\left(x-1\right)\left(\sqrt{2x-1}-3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-1=0\\\sqrt{2x-1}-3=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=1\\2x-1=9\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=1\\x=5\end{matrix}\right.\)
d/ ĐKXĐ: \(1\le x< 3\)
\(\Leftrightarrow\sqrt{-x^2+4x-3}-1=2x-6\)
\(\Leftrightarrow\sqrt{-x^2+4x-3}=2x-5\) (\(x\ge\frac{5}{2}\))
\(\Leftrightarrow-x^2+4x-3=\left(2x-5\right)^2\)
\(\Leftrightarrow5x^2-24x+28=0\)
\(\Rightarrow\left[{}\begin{matrix}x=2< \frac{5}{2}\left(l\right)\\x=\frac{14}{5}\end{matrix}\right.\)
e/ ĐKXĐ: \(\left\{{}\begin{matrix}x\ge-1\\x\ne2\end{matrix}\right.\)
\(\Leftrightarrow5+\sqrt{x+1}=7x-14\)
\(\Leftrightarrow\sqrt{x+1}=7x-19\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge\frac{19}{7}\\x+1=\left(7x-19\right)^2\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge\frac{19}{7}\\49x^2-267x+360=0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=3\\x=\frac{120}{49}< \frac{19}{7}\left(l\right)\end{matrix}\right.\)
Giai PT
A=\(\sqrt{4x+1}-\sqrt{3x-2}=\frac{x+3}{2}\)
\(A=\sqrt{4x+1}-\sqrt{3x-2}=\frac{x+3}{2}\)
đkxđ \(\hept{\begin{cases}x\ge-\frac{1}{4}\\x\ge\frac{2}{3}\end{cases}}\)
đặt t=x+3 phương trình trở thành
\(A=\sqrt{4\left[x+3\right]-11}-\sqrt{3\left[x+3\right]-11}=\frac{x+3}{2}\)
\(A=\sqrt{4t-11}-\sqrt{3t-11}=\frac{t}{2}\)
\(\Leftrightarrow4t-11=\frac{t^2}{4}+3t-11+t\sqrt{3t-11}\)
\(\Leftrightarrow t^2-\frac{t^2}{4}=t\sqrt{3t-11}\)
\(\Leftrightarrow\frac{t\left[4-t\right]}{4}=t\sqrt{3t-11}\)
\(\Leftrightarrow\frac{\left[4-t\right]^2}{16}=3t-11\)
\(\Leftrightarrow t^2-56t+192=0\)
\(\Leftrightarrow\orbr{\begin{cases}t=28+4\sqrt{37}\\t=28-4\sqrt{37}\end{cases}}\)
thế vào x+3=t suy ra
\(\orbr{\begin{cases}x=25+4\sqrt{37}\left[loại\right]\\x=25-4\sqrt{37}\left[nhận\right]\end{cases}}\)
\(S=\left\{25-4\sqrt{37}\right\}\)
2. Giải PT:
a) \(\frac{9x-7}{\sqrt{7x+5}}=\sqrt{7x+5}.\)
b) \(\sqrt{4x-20}+3\sqrt{\frac{x-5}{9}}-\frac{1}{3}\sqrt{9x-45}=4.\)
c) \(2x-x^2+\sqrt{6x^2-12x+7}=0.\)
d) \(\left(x+1\right)\left(x+4\right)-3\sqrt{x^2+5x+2}=6.\)
\(a,\frac{9x-7}{\sqrt{7x+5}}=\sqrt{7x+5}\)\(ĐKXĐ:x\ge-\frac{5}{7}\)
\(\Leftrightarrow9x-7=7x+5\)
\(\Leftrightarrow9x-7x=5+7\)
\(\Leftrightarrow2x=12\)
\(\Leftrightarrow x=6\)
\(b,\sqrt{4x-20}+3\sqrt{\frac{x-5}{9}}-\frac{1}{3}\sqrt{9x-45}=4\)
\(\Leftrightarrow\sqrt{4\left(x-5\right)}+3.\frac{\sqrt{x-5}}{\sqrt{9}}-\frac{1}{3}\sqrt{9\left(x-5\right)}=4\)
\(\Leftrightarrow2\sqrt{x-5}+\sqrt{x-5}-\sqrt{x-5}=4\)
\(\Leftrightarrow\sqrt{x-5}\left(2+1-1\right)=4\)
\(\Leftrightarrow2\sqrt{x-5}=4\)
\(\Leftrightarrow\sqrt{x-5}=2\)
\(\Leftrightarrow x-5=4\)
\(\Leftrightarrow x=9\)
\(\sqrt{4x-20}+3\sqrt{\dfrac{x-5}{9}}-\dfrac{1}{3}\sqrt{9x-45}=4\)giải hộ mik pt này
\(2\sqrt{x-5}+\sqrt{x-5}-\sqrt{x-5}=4\)
\(2\sqrt{x-5}=4\)
\(\sqrt{x-5}=2\)
\(\left\{{}\begin{matrix}2>0\left(luondung\right)\\x-5=4\end{matrix}\right.\)\(\Rightarrow x=9\left(tm\right)\)
Giải pt
\(\sqrt{4x+20}-3\sqrt{5+x}+\frac{4}{3}\sqrt{9x+45}=6\)
ĐKXĐ: \(x\ge-5\)
\(\Leftrightarrow\sqrt{4\left(x+5\right)}-3\sqrt{x+5}+\frac{4}{3}\sqrt{9\left(x+5\right)}=6\)
\(\Leftrightarrow2\sqrt{x+5}-3\sqrt{x+5}+4\sqrt{x+5}=6\)
\(\Leftrightarrow3\sqrt{x+5}=6\)
\(\Leftrightarrow\sqrt{x+5}=2\)
\(\Leftrightarrow x+5=4\Rightarrow x=-1\)