TIM X BIET(X-2)^3-X^3+6X^2=7
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<=>x^3-6x^2+12x-8-x^3+6x^2=7
<=>12x=15
<=> x=5/4
chúc bạn hk tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
Tim x,
a,2x^4-6x^3+x^2+6x-3=0
b,x^3-9x^2+26x+24=0
c, P= 2x^4 - 4x^3 + 6x^2 - 4x + 5 biet rang x^2 - x=7
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(2x^4-6x^3+x^2+6x-3=0\)
\(\Leftrightarrow2x^4-6x^3+3x^2-2x^2+6x-3=0\)
\(\Leftrightarrow x^2\left(2x^2-6x+3\right)-\left(2x^2-6x+3\right)=0\)
\(\Leftrightarrow\left(x^2-1\right)\left(2x^2-6x+3\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(2x^2-6x+3\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-1=0\\x+1=0\\2x^2-6x+3=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=1\\x=-1\\\Delta_{2x^2-6x+3}=\left(-6\right)^2-4\left(2.3\right)=12\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=1\\x=-1\\x_{1,2}=\frac{6\pm\sqrt{12}}{4}\end{array}\right.\)
b)\(x^3+9x^2+26x+24=0\)
\(\Leftrightarrow x^3+5x^2+6x+4x^2+20x+24=0\)
\(\Leftrightarrow x\left(x^2+5x+6\right)+4\left(x^2+5x+6\right)=0\)
\(\Leftrightarrow\left(x^2+5x+6\right)\left(x+4\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left(x+3\right)\left(x+4\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x+2=0\\x+3=0\\x+4=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=-2\\x=-3\\x=-4\end{array}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a/
\(-24+\left(x+4\right)^4=10^3\)3
\(\Leftrightarrow-24+x^4+16x^3+96x^2+256x+256=10^3\)
<=>\(x^4+16x^3+96x^2+256x-768=0\)
Giải trên tập số phức ta được
\(x=-\sqrt{32}-4\)
\(x=\sqrt{32}-4\)
\(x=-\sqrt{32}i-4\)
\(x=\sqrt{32}1-4\)=> Phần a kog có giá trị nguyên nào của x thỏa mãn phương trình
b/
2(x+7)-3(6-x)=-24
<=> 2x+14-18+3x=-24
<=>5x=-20
<=>x=-4
Vậy x=-4
c/
\(3x-6x^2=0\)
\(\Leftrightarrow3x\left(1-2x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3x=0\\1-2x=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{2}\end{cases}}\)(x = 1/2 kog thỏa mãn yêu cầu)
Vậy x=0
a/\(\left(x+4\right)^4=1000+24\)
\(\Rightarrow x^4+8x^2+4^4-1024=0\)
\(\Rightarrow x^4+8x^2-768\)
\(\Rightarrow x^4-24x+32x-768=0\)
\(\Rightarrow x.\left(x-24\right)+32.\left(x-24\right)\)
\(\Rightarrow\left(x+32\right).\left(x-24\right)\Rightarrow\orbr{\begin{cases}x=-32\\x=24\end{cases}}\)
b/2x+14-18+3x=-24
5x=-24-14+18
x=-20/5=-4
c/3x-6x\(^2\) =0
\(3x.\left(1-2x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x=0\rightarrow x=0\\1-2x=0\rightarrow x=\frac{1}{2}\end{cases}}\)
KL bAN tu lam nhe
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow\left(2x+3-2x+5\right)^2=x^2+6x+64\)
=>x^2+6x=0
=>x(x+6)=0
=>x=0 hoặc x=-6
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(3-\sqrt{2x}\right)\left(2-3\sqrt{2x}\right)=6x-5\)ĐK : x>= 0
\(\Leftrightarrow6-9\sqrt{2x}-2\sqrt{2x}+6x=6x-5\)
\(\Leftrightarrow-11\sqrt{2x}+6x+6=6x-5\Leftrightarrow-11\sqrt{2x}=-11\)
\(\Leftrightarrow\sqrt{2x}=1\Leftrightarrow2x=1\Leftrightarrow x=\dfrac{1}{2}\left(tm\right)\)
giải hằng đẳng thức rồi rút gọn tìm x nhé