\(2x\left(8x-1\right)^2\left(4x-1\right)=9\)

\(\Leftrightarrow8x\left(8x-1\right)^2\left(8x-2\right)=72\)(nhân hai vế với 8)

Đặt \(8x-1=y\). Khi đó, pt được viết lại:

\(\left(y+1\right)y^2\left(y-1\right)=72\)

\(\Leftrightarrow y^2\left(y^2-1\right)=72\)

\(\Leftrightarrow y^4-y^2-72=0\)

\(\Leftrightarrow y^4+3y^3-3y^3-9y^2+8y^2+24y-24y-72=0\)

\(\Leftrightarrow y^3\left(y+3\right)-3y^2\left(y+3\right)+8y\left(y+3\right)-24\left(y+3\right)=0\)

\(\Leftrightarrow\left(y+3\right)\left(y^3-3y^2+8y-24\right)=0\)

\(\Leftrightarrow\left(y+3\right)\left(y^2\left(y-3\right)+8\left(y-3\right)\right)=0\)

\(\Leftrightarrow\left(y+3\right)\left(y-3\right)\left(y^2+8\right)=0\)

Mà \(y^2+8\ge8>0\)

\(\Rightarrow\orbr{\begin{cases}y+3=0\\y-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}y=-3\\y=3\end{cases}}}\)

TH1: \(y=-3\)

\(\Rightarrow8x-1=-3\)

\(\Leftrightarrow8x=-2\)

\(\Leftrightarrow x=\frac{-1}{4}\)

TH2: \(y=3\)

\(\Rightarrow8x-1=3\)

\(\Leftrightarrow8x=4\)

\(\Leftrightarrow x=\frac{1}{2}\)

Vậy tập nghiệm của pt là S={\(\frac{-1}{4};\frac{1}{2}\)}

1: \(\Leftrightarrow\left(x-4\right)^2+14=-9\left(x-4\right)\)

\(\Leftrightarrow x^2-8x+16+14+9x-36=0\)

\(\Leftrightarrow x^2+x-6=0\)

=>(x+3)(x-2)=0

=>x=-3(nhận) hoặc x=2(nhận)

2: \(\Leftrightarrow\left(8x+1\right)\left(2x-1\right)-2x\left(2x+1\right)-12x^2+9=0\)

\(\Leftrightarrow16x^2-8x+2x-1-4x^2-2x-12x^2+9=0\)

=>-8x+8=0

hay x=1(nhận)

c: \(\dfrac{1}{2\left(x-3\right)}-\dfrac{3x-5}{\left(x-3\right)\left(x-1\right)}=\dfrac{1}{2}\)

\(\Leftrightarrow x-1-2\left(3x-5\right)=\left(x-3\right)\left(x-1\right)\)

\(\Leftrightarrow x^2-4x+3=x-1-6x+10=-5x+9\)

\(\Leftrightarrow x^2+x-6=0\)

=>(x+3)(x-2)=0

=>x=-3(nhận) hoặc x=2(nhận)

 Nhows k cho mình nhá

\(PT< =>8x\left(8x-1\right)^2\left(8x-2\right)=72\)

\(< =>8x\left(8x-2\right)\left(64x^2-16x+1\right)=72\)

\(< =>\left(64x^2-16x\right)\left(64x^2-16x+1\right)=72\)

Đặt \(64x^2-16x+\frac{1}{2}=t\)

\(PT< =>\left(t-\frac{1}{2}\right)\left(t+\frac{1}{2}\right)=72\)

\(< =>t^2=\frac{289}{4}\)

\(< =>\orbr{\begin{cases}t=\frac{17}{2}\\t=\frac{-17}{2}\end{cases}}\)

\(TH1:t=\frac{17}{2}\)

\(PT< =>64x^2-16x+\frac{1}{2}=\frac{17}{2}\)

\(< =>\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{-1}{4}\end{cases}}\)

\(TH2:t=\frac{-17}{2}\)

\(PT< =>64x^2-16x+\frac{1}{2}=\frac{-17}{2}\)

\(< =>64x^2-16x+9=0\)

\(< =>\left(8x-1\right)^2+8=0\left(VL\right)\)

Vậy S={1/2;-1/4}

x = -0.25 và hình như còn 1 giá trị nữa hay sao ý ạ

Trả lời:

\(\frac{x-1}{2x^2-4x}-\frac{7}{8x}=\frac{5-x}{4x^2-8x}-\frac{1}{8x-16}\)\(\left(đkxđ:x\ne0;x\ne2\right)\)

\(\Leftrightarrow\frac{x-1}{2x\left(x-2\right)}-\frac{7}{8x}=\frac{5-x}{4x\left(x-2\right)}-\frac{1}{8\left(x-2\right)}\)

\(\Leftrightarrow\frac{4\left(x-1\right)}{8x\left(x-2\right)}-\frac{7\left(x-2\right)}{8x\left(x-2\right)}=\frac{2\left(5-x\right)}{8x\left(x-2\right)}-\frac{x}{8x\left(x-2\right)}\)

\(\Rightarrow4\left(x-1\right)-7\left(x-2\right)=2\left(5-x\right)-x\)

\(\Leftrightarrow4x-4-7x+14=10-2x-x\)

\(\Leftrightarrow10-3x=10-3x\)

\(\Leftrightarrow-3x+3x=10-10\)

\(\Leftrightarrow0x=0\)( luôn thỏa mãn )

Vậy S = R với \(x\ne0;x\ne2\)

2x(8x-1)²(4x-1)= 9

<=> 2x(64x²-16x+1)(4x-1)=9

<=>(128x³  - 32x² + 2x)(4x-1)=9

<=>512x⁴ - 256x³ + 40x²  - 2x=9

<=>64x⁴ - 32x³ + 5x² - 0,25x - 1,125=0

<=>64x³(x-0,5) + 5x(x-0,5) + 2,5x  -0,25x - 1,125 = 0

<=> (x-0,5)(64x³ + 5x - 2,25) = 0

<=> (x-0,5)(64x³  + 16x² - 16x² - 4x + 9x - 2,25)=0

<=>(x-0,5)[64x² (x + 0,25 ) -16x(x + 0,25) + 9(x + 0,25) = 0

<=> (x-0,5)(x+0,25)(64x² -16x +9) = 0  (vì 64x² -16x +9 > 0)

<=>\(\orbr{\begin{cases}x-0,5=0\\x+0,25=0\end{cases}}\)

<=>\(\orbr{\begin{cases}x=0,5\\x=-0,25\end{cases}}\)

Vậy phương trình có hai nghiệm là S={\(\frac{1}{2}\) ; \(\frac{-1}{4}\)}

\(\Leftrightarrow8x\left(8x-1\right)^2\left(8x-2\right)=72.\)(nhân cả 2 vế vs 8)

Đặt \(a=8x-1.\)ta có pt

\(\left(a-1\right)a^2\left(a+1\right)=72\)

\(\Leftrightarrow a^4-a^2-72=0\)

\(\Leftrightarrow\left(a^2-9\right)\left(a^2+8\right)=0.\)

\(\Rightarrow\left(a-3\right)\left(a+3\right)=0\)(do \(a^2+8\ne0.\))

\(\Rightarrow\orbr{\begin{cases}a=3\\a=-3\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}8x-1=3\\8x-1=-3\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=0.5\\x=-0.25\end{cases}}\)

vậy, \(S=\left\{0.5;-0.25\right\}.\)

xong rồi đó bn

ko có dấu cộng hay dấu trừ j ak