Phuong trinh nay nhan lien hop a
\(\sqrt{x^2+3}+\frac{4x}{\sqrt{x^2+3}}=5\sqrt{x}\)
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\(DK:x\ge0\)
\(\Leftrightarrow\frac{\sqrt{x}-\sqrt{x+1}}{x-x-1}+\frac{\sqrt{x+1}-\sqrt{x+2}}{x+1-x-2}+\frac{\sqrt{x+2}-\sqrt{x+3}}{x+2-x-3}=1\)
\(\Leftrightarrow-\sqrt{x}+\sqrt{x+1}-\sqrt{x+1}+\sqrt{x+2}-\sqrt{x+2}+\sqrt{x+3}=1\)
\(\Leftrightarrow\sqrt{x+3}-\sqrt{x}=1\)
\(\Leftrightarrow\sqrt{x+3}=1+\sqrt{x}\)
\(\Leftrightarrow x+3=x+2\sqrt{x}+1\)
\(\Leftrightarrow x=1\)
Vay nghiem cua PT la \(x=1\)
a: ĐKXĐ: x>=0
b: \(\Leftrightarrow\dfrac{2\sqrt{2}-2\sqrt{2-\sqrt{x}}+\sqrt{2x}-\sqrt{x\left(2-\sqrt{x}\right)}+2\sqrt{2}+2\sqrt{2+\sqrt{x}}-\sqrt{2x}-\sqrt{x\left(2+\sqrt{x}\right)}}{2-2+\sqrt{x}}=\sqrt{2}\)
\(\Leftrightarrow4\sqrt{2}-2\sqrt{x\left(\sqrt{x}+2\right)}=\sqrt{2x}\)
\(\Leftrightarrow\sqrt{4x\left(\sqrt{x}+2\right)}=4\sqrt{2}-\sqrt{2x}\)
\(\Leftrightarrow4x\left(\sqrt{x}+2\right)=32-16\sqrt{x}+2x\)
\(\Leftrightarrow4x\sqrt{x}+8x-32+16\sqrt{x}-2x=0\)
=>\(x\in\left\{0;1.2996\right\}\)
a.
\(\sqrt{4x^2+4x+1}-\sqrt{25x^2+10x+1}=0\)
\(\Leftrightarrow\sqrt{\left(2x+1\right)^2}-\sqrt{\left(5x+1\right)^2}=0\)
\(\Leftrightarrow2x+1-\left(5x+1\right)=0\)
\(\Leftrightarrow-3x=0\Leftrightarrow x=0\)
b.
\(\sqrt{x^4-16x^2+64}=\sqrt{25x^2+10x+1}\)
\(\Leftrightarrow\sqrt{\left(x^2-8\right)^2}=\sqrt{\left(5x+1\right)^2}\)
\(\Leftrightarrow x^2-8=5x+1\)
\(\Leftrightarrow x^2-5x+\dfrac{25}{4}=\dfrac{61}{4}\)
\(\Leftrightarrow\left(x-\dfrac{5}{2}\right)^2=\dfrac{61}{4}\)
............................
tương tự ..
c: \(\Leftrightarrow\sqrt{x-5}\left(\sqrt{x+5}-1\right)=0\)
=>x-5=0 hoặc x+5=1
=>x=-4 hoặc x=5
d: \(\Leftrightarrow\sqrt{2x+3}\left(\sqrt{2x-3}-2\right)=0\)
=>2x+3=0 hoặc 2x-3=4
=>x=7/2 hoặc x=-3/2
e: \(\Leftrightarrow\sqrt{x-2}\left(1-3\sqrt{x+2}\right)=0\)
=>x-2=0 hoặc 3 căn x+2=1
=>x=2 hoặc x+2=1/9
=>x=-17/9 hoặc x=2
Pt tương đương:
\(\sqrt[3]{4x-3}\)-\(\sqrt[3]{3x+1}\)=\(\sqrt[3]{5-x}\)+\(\sqrt[3]{2x-9}\)
\(\Leftrightarrow\)-3\(\sqrt[3]{\text{(4x-3)(3x+1)}}\)(\(\sqrt[3]{4x-3}\)-\(\sqrt[3]{3x+1}\))=3\(\sqrt[3]{\left(5-x\right)\left(2x-9\right)}\)(\(\sqrt[3]{5-x}\)+\(\sqrt[3]{2x-9}\))
\(\Leftrightarrow\)\(\orbr{\begin{cases}\sqrt[3]{4x-3}-\sqrt[3]{3x+1}=\sqrt[3]{5-x}+\sqrt[3]{2x-9}=0\left(1\right)\\3\sqrt[3]{-12x^2+5x+3}=3\sqrt[3]{-2x^2+19x-45}\left(2\right)\end{cases}}\)
(1)<=>4x-3=3x+1 và x-5=2x-9<=>x=4
(2)<=>-12x2+5x+3=-2x2+19x-45<=>-5x2-7x+24=0<=>x=8/5 và x=-3
bạn thử các giá trị x=4,x=8/5 và x=-3 vào pt và kết luận
mik ko hieu vi sao ban suy ra duoc (1) va (2)
bn co the viet ro ra duoc ko ?
theo mik thay thi 2 pt do dau co tuong duong
\(\sqrt{x^2+3}+\frac{4x}{\sqrt{x^2+3}}=5\sqrt{x}\)
\(\frac{\sqrt{x^2+3}.\sqrt{x^2+3}}{\sqrt{x^2+3}}+\frac{4x}{\sqrt{x^2+3}}=5\sqrt{x}\)
\(\frac{\sqrt{\left(x^2+3\right)\left(x^2+3\right)}}{\sqrt{x^2+3}}+\frac{4x}{\sqrt{x^2+3}}=\frac{5\sqrt{x.\left(x^2+3\right)}}{\sqrt{x^2+3}}\)
\(\frac{\sqrt{\left(x^2+3\right)^2}}{\sqrt{x^2+3}}+\frac{4x}{\sqrt{x^2+3}}=\frac{3\sqrt{x\left(x^2+3\right)}}{\sqrt{x^2+3}}\)
\(\Leftrightarrow\)\(x^2+4x+3=3\sqrt{x\left(x^2+3\right)}\)
\(\Leftrightarrow\left(x^2+4x+3\right)^2=\left[3\sqrt{x\left(x^2+3\right)}\right]^2\)
\(\Leftrightarrow x^4+8x^3+9=9.\left(x^3+3x\right)\)
\(\Leftrightarrow x^4+8x^3+9=9x^3+27x\)
\(\Leftrightarrow x^4+8x^3-9x^3-27x+9=0\)
\(\Leftrightarrow x^4-x^3-27x+9=0\)
\(\Leftrightarrow\left(x^4-27x\right)-\left(x^3-9\right)=0\)
\(\Leftrightarrow x\left(x^3-27\right)-\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow x\left(x-3\right)\left(x^2+3x+9\right)-\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left(x-3\right).\left[x\left(x^2+3x+9\right)-x-3\right]=0\)
\(\Leftrightarrow\left(x-3\right).\left[x^3+3x^2+9x-x-3\right]=0\)
\(\Leftrightarrow\left(x-3\right).\left[x^3+3x^2+8x-3\right]=0\)
Sao ở vế phải đang từ \(\frac{5\sqrt{x\left(x^2+3\right)}}{x^2+3}\) lại thành \(\frac{3\sqrt{x\left(x^2+3\right)}}{x^2+3}\)