a:Sửa đề: \(\dfrac{3}{5x-1}+\dfrac{2}{3-x}=\dfrac{4}{\left(1-5x\right)\left(x-3\right)}\)

=>3x-9-10x+2=-4

=>-7x-7=-4

=>-7x=3

=>x=-3/7

b: =>\(\dfrac{5-x}{4x\left(x-2\right)}+\dfrac{7}{8x}=\dfrac{x-1}{2x\left(x-2\right)}+\dfrac{1}{8\left(x-2\right)}\)

=>\(2\left(5-x\right)+7\left(x-2\right)=4\left(x-1\right)+x\)

=>10-2x+7x-14=4x-4+x

=>5x-4=5x-4

=>0x=0(luôn đúng)

Vậy: S=R\{0;2}

roois vãi

-Đăng tách câu hỏi bạn nhé.

c:

ĐKXĐ: 6-5x>=0

=>5x<=6

=>x<=1,2

\(2\sqrt[3]{3x-2}-3\cdot\sqrt{6-5x}+16=0\)

=>\(2\cdot\sqrt[3]{3x-2}+4+12-3\cdot\sqrt{6-5x}=0\)

=>\(2\cdot\left(\sqrt[3]{3x-2}+2\right)+3\left(4-\sqrt{6-5x}\right)=0\)

=>\(2\cdot\frac{3x-2+8}{\sqrt[3]{\left(3x-2\right)^2}-2\cdot\sqrt[3]{3x-2}+4}+3\cdot\frac{16-6+5x}{4+\sqrt{6-5x}}=0\)

=>\(2\cdot\frac{3x+6}{\sqrt[3]{\left(3x-2\right)^2}-2\cdot\sqrt[3]{3x-2}+4}+3\cdot\frac{5x+10}{4+\sqrt{6-5x}}=0\)

=>\(\left(2\cdot\frac{3}{\sqrt[3]{\left(3x-2\right)^2}-2\cdot\sqrt[3]{3x-2}+4}+3\cdot\frac{5}{4+\sqrt{6-5x}}\right)\left(x+2\right)=0\)

=>x+2=0

=>x=-2(nhận)

d: ĐKXĐ: x>=1

\(\sqrt[3]{x+6}-2\cdot\sqrt{x-1}=4-x^2\)

=>\(\sqrt[3]{x+6}-2-2\cdot\sqrt{x-1}+2=4-x^2\)

=>\(\frac{x+6-8}{\sqrt[3]{\left(x+6\right)^2}+2\cdot\sqrt[3]{x+6}+4}+2\left(1-\sqrt{x-1}\right)=\left(2-x\right)\left(2+x\right)\)

=>\(\frac{x-2}{\sqrt[3]{\left(x+6\right)^2}+2\cdot\sqrt[3]{x+6}+4}+2\cdot\frac{1-x+1}{1+\sqrt{x-1}}=\left(2-x\right)\left(2+x\right)\)

=>\(\frac{x-2}{\sqrt[3]{\left(x+6\right)^2}+2\cdot\sqrt[3]{x+6}+4}-2\cdot\frac{x-2}{1+\sqrt{x-1}}-\left(2-x\right)\left(2+x\right)=0\)

=>\(\frac{x-2}{\sqrt[3]{\left(x+6\right)^2}+2\cdot\sqrt[3]{x+6}+4}-2\cdot\frac{x-2}{1+\sqrt{x-1}}+\left(x-2\right)\left(2+x\right)=0\)

=>\(\left(x-2\right)\left(\frac{1}{\sqrt[3]{\left(x+6\right)^2}+2\cdot\sqrt[3]{x+6}+4}-\frac{2}{1+\sqrt{x-1}}+\left(2+x\right)\right)=0\)

=>x-2=0

=>x=2(nhận)

bấm máy tính nha...

PT trên vô nghiệm

\(x^4-4x^3-x^3+4x^2+4x^2-4x-x+1=0\)0

\(x^3\left(x-4\right)-x^2\left(x-4\right)+4x\left(x-1\right)-\left(x-1\right)\)=0

\(\left(x^3-x^2\right)\cdot\left(x-4\right)+\left(4x-1\right)\cdot\left(x-1\right)=0\)

\(x^2\left(x-1\right)\cdot\left(x-4\right)+\left(4x-1\right)\cdot\left(x-1\right)=0\)

\(\left(x-1\right)\cdot\left(x^3-4x^2+4x-1\right)=0\)

\(x=1\)

Phương trình đã cho có dạng:

\(ax^4+bx^3+cx^2+a=0\left(a\ne0\right)\)

Đặt \(x+\frac{1}{x}=y\) ta đưa phương trình về dạng:\(y^2-5y+6=0\)

Giải phương trình bậc hai theo y ta có:\(y_1=2;y_2=3\)

Do đó:

\(x+\frac{1}{x}=2\Rightarrow x^2-2x+1=0\Rightarrow x_o=1\)

\(x+\frac{1}{x}=3\Rightarrow x^2-3x+1=0\Rightarrow x_1=\frac{3-\sqrt{5}}{2};x_2=\frac{3+\sqrt{5}}{2}\)

Vậy phương trình đã cho có ba nghiệm là:

\(x_o=1;x_1=\frac{3-\sqrt{5}}{2};x_2=\frac{3+\sqrt{5}}{2}\)(x_o là nghiệm kép).

a: Ta có: \(x^2+3x+4=0\)

\(\text{Δ}=3^2-4\cdot1\cdot4=9-16=-7< 0\)

Do đó: Phương trình vô nghiệm

a: \(x^4=5x^2+2x-3\)

=>\(x^4-5x^2-2x+3=0\)

=>\(x^4+x^3-x^2-x^3-x^2+x-3x^2-3x+3=0\)

=>\(\left(x^2+x-1\right)\left(x^2-x-3\right)=0\)

TH1: \(x^2+x-1=0\)

=>\(x^2+x+\frac14=\frac54\)

=>\(\left(x+\frac12\right)^2=\frac54\)

=>\(x+\frac12=\pm\frac{\sqrt5}{2}\)

=>\(x=-\frac12\pm\frac{\sqrt5}{2}\)

TH2: \(x^2-x-3=0\)

=>\(x^2-x+\frac14-\frac{13}{4}=0\)

=>\(\left(x-\frac12\right)^2=\frac{13}{4}\)

=>\(x-\frac12=\pm\frac{\sqrt{13}}{2}\)

=>\(x=\frac12\pm\frac{\sqrt{13}}{2}\)

c: \(3x^3+3x^2+3x=-1\)

=>\(x^3+3x^2+3x+1=-2x^3\)

=>\(\left(x+1\right)^3=\left(x\cdot\sqrt[3]{-2}\right)^3\)

=>\(x+1=x\cdot\sqrt[3]{-2}\)

=>\(x\left(1-\sqrt[3]{-2}\right)=-1\)

=>\(x=\frac{-1}{1-\sqrt[3]{-2}}\)

d: \(8x^3-12x^2+6x-5=0\)

=>\(8x^3-12x^2+6x-1-4=0\)

=>\(\left(2x-1\right)^3=4\)

=>\(2x-1=\sqrt[3]{4}\)

=>\(2x=1+\sqrt[3]{4}\)

=>\(x=\frac12+\frac12\cdot\sqrt[3]{4}\)