X3 --17x-24=0
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a. (3x - 1)2 - (x + 3)2 = 0
\(\Leftrightarrow\left(3x-1+x+3\right)\left(3x-1-x-3\right)=0\)
\(\Leftrightarrow\left(4x+2\right)\left(2x-4\right)=0\)
\(\Leftrightarrow4x+2=0\) hoặc \(2x-4=0\)
1. \(4x+2=0\Leftrightarrow4x=-2\Leftrightarrow x=-\dfrac{1}{2}\)
2. \(2x-4=0\Leftrightarrow2x=4\Leftrightarrow x=2\)
S=\(\left\{-\dfrac{1}{2};2\right\}\)
b. \(x^3=\dfrac{x}{49}\)
\(\Leftrightarrow49x^3=x\)
\(\Leftrightarrow49x^3-x=0\)
\(\Leftrightarrow x\left(49x^2-1\right)=0\)
\(\Leftrightarrow x\left(7x+1\right)\left(7x-1\right)=0\)
\(\Leftrightarrow x=0\) hoặc \(7x+1=0\) hoặc \(7x-1=0\)
1. x=0
2. \(7x+1=0\Leftrightarrow7x=-1\Leftrightarrow x=-\dfrac{1}{7}\)
3. \(7x-1=0\Leftrightarrow7x=1\Leftrightarrow x=\dfrac{1}{7}\)
a: x^3-2x-4=0
=>x^3-2x^2+2x^2-4x+2x-4=0
=>(x-2)(x^2+2x+2)=0
=>x-2=0
=>x=2
b: 2x^3-12x^2+17x-2=0
=>2x^3-4x^2-8x^2+16x+x-2=0
=>(x-2)(2x^2-4x+1)=0
=>x=2; \(x=\dfrac{4\pm\sqrt{14}}{2}\)
a: =>5x-5+17x=1-12x-4
=>22x-5=-12x-3
=>34x=2
hay x=1/17
b: =>\(\left(x-3\right)^2-4x\left(x-3\right)=0\)
=>(x-3)(-3x-3)=0
=>x=3 hoặc x=-1
c: =>(x-4)(x-6)=0
=>x=4 hoặc x=6
=>|17x-5|=|17x+5|
=>17x-5=17x+5(vô lý) hoặc 17x-5=-17x-5
=>34x=0
hay x=0
\(\left|17x-5\right|=\left|17x+5\right|\)
\(\Leftrightarrow\left[{}\begin{matrix}17x-5=17x+5\\17x-5=-5-17x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}-5=5\left(loai\right)\\34x=0\end{matrix}\right.\Leftrightarrow x=0\)
\(\Leftrightarrow x^4+3x^3-4x^2+5x^3+15x^2-20x+6x^2+18x-24=0\)
\(\Leftrightarrow x^2\left(x^2+3x-4\right)+5x\left(x^2+3x-4\right)+6\left(x^2+3x-4\right)=0\)
\(\Leftrightarrow\left(x^2+3x-4\right)\left(x^2+5x+6\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+4\right)\left(x+2\right)\left(x+3\right)=0\)
Phương trình tương đương : \(\)\(⇔ x 4 + 3 x 3 − 4 x 2 + 5 x 3 + 15 x 2 − 20 x + 6 x 2 + 18 x − 24 = 0 ⇔ x 2 ( x 2 + 3 x − 4 ) + 5 x ( x 2 + 3 x − 4 ) + 6 ( x 2 + 3 x − 4 ) = 0 ⇔ ( x 2 + 3 x − 4 ) ( x 2 + 5 x + 6 ) = 0 ⇔ ( x − 1 ) ( x + 4 ) ( x + 2 ) ( x + 3 ) = 0\)
x3 - 9x - 8x - 24 = 0
<=> x(x2 - 9) - 8(x + 3) = 0
<=> x(x - 3)(x + 3) - 8(x + 3) = 0
<=> (x + 3)(x2 - 3x - 8) = 0
<=> \(\left(x+3\right)\left(x^2-2.\frac{3}{2}x+\frac{9}{4}-\frac{41}{4}\right)=0\)
<=> \(\left(x+3\right)\left[\left(x-\frac{3}{2}\right)^2-\left(\frac{\sqrt{41}}{2}\right)^2\right]=0\)
<=> \(\left(x+3\right)\left(x-\frac{3}{2}+\frac{\sqrt{41}}{2}\right)\left(x-\frac{3}{2}-\frac{\sqrt{41}}{2}\right)=0\)
<=> \(\orbr{\begin{cases}x=-3\\x=\frac{3\pm\sqrt{41}}{2}\end{cases}}\)