![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)x=-2
b)x=1
c)x=1/2
f)x=1 hoặc x=-1
h)x=0 hoặc x=6
i)x=2
hok tốt!
_Lan Lan_
Áp dụng hằng đẳng thức:\(\left(a+b\right)^3=a^3+3a^2b+3ab^2+b^3\)
\(\left(a-b\right)^3=a^3-3a^2b+3ab^2-b^3\)
Áp dụng vào từng bài là được:
\(VD1:x^3+3x^2+3x+1=-1\)
\(\Rightarrow\left(x+1\right)^3=-1\)
\(\Rightarrow x=-2\)
\(VD2:x^3-9x^2+27x-27=-8\)
\(\Rightarrow\left(x-3\right)^3=-8\)
\(\Rightarrow x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,-x^3+3x^2-3x+1=-\left(x^3-3x^2+3x-1\right)=-\left(x^3-3.x^2.1+3.x.1^2-1^3\right)\)
\(=-\left(x-1\right)^3\)
\(b,8-12x+6x^2-x^3=2^3-3.2^2.x+3.2.x^2-x^3=\left(2-x\right)^3\)
\(a,x^3+12x^2+48x+64=x^3+3.x^2.4+3.x.4^2+4^3=\left(x+4\right)^3=\left(6+4\right)^3=10^3=1000\)
\(b,x^3-6x^2+12x-8=x^3-3.x^2.2+3.x.2^2-2^3=\left(x-2\right)^3=\left(22-2\right)^3=20^3=8000\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(3x^2+6x-2x^5:2x^4+3x:2x\)
=\(3x^2+6x+9-2x+1,5x\)
=\(3x^2+\left(6x-2x+1,5x\right)+9\)
=\(3x^2+5,5x+9\)
b)\(4x^2y^2+y^3-2x-y^3+5x-3x^2y^3\)
= \(4x^2y^2-3x^2y^3+\left(y^3-y^3\right)+\left(-2x+5x\right)\)
= \(4x^2y^2-3x^2y^3+3x\)
c)\(18x+26x^2-48x^2+1x^3-5x^2-17x-x^4\cdot x^2-4x^6\)
= \(\left(18x-17x\right)+\left(26x^2-48x^2-5x^2\right)+1x^3+\left(-4x^6-x^4\cdot x^2\right)\)
= \(x-27^2+x^3-5x^6\)
d) \(y^2-109y+27y+18y^2-7y^2+52y+9+4y^3-3y^2\cdot y^3+15y\)
= \(\left(y^2-7y^2+18y^2\right)+\left(-109y+27y+52y+15y\right)+9+4y^3-3y^5\)
= \(12y^2-15y+9+4y^3-3y^5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: (2x-3)(3x+6)>0
=>(2x-3)(x+2)>0
=>x<-2 hoặc x>3/2
b: (3x+4)(2x-6)<0
=>(3x+4)(x-3)<0
=>-4/3<x<3
c: (3x+5)(2x+4)>4
\(\Leftrightarrow6x^2+12x+10x+20-4>0\)
\(\Leftrightarrow6x^2+22x+16>0\)
=>\(6x^2+6x+16x+16>0\)
=>(x+1)(3x+8)>0
=>x>-1 hoặc x<-8/3
f: (4x-8)(2x+5)<0
=>(x-2)(2x+5)<0
=>-5/2<x<2
h: (3x-7)(x+1)<=0
=>x+1>=0 và 3x-7<=0
=>-1<=x<=7/3
![](https://rs.olm.vn/images/avt/0.png?1311)
b) \(\left|4-7x\right|-\dfrac{3}{2}:5=\left|-1\dfrac{1}{3}\right|\)
\(\left|4-7x\right|-\dfrac{3}{10}=\dfrac{4}{3}\)
\(\left|4-7x\right|=\dfrac{49}{30}\) (*)
+) Nếu 4 - 7x \(\ge\) 0 \(\Rightarrow x\le\dfrac{4}{7}\)
PT (*) \(\Leftrightarrow4-7x=\dfrac{49}{30}\)
\(-7x=-\dfrac{71}{30}\)
x = \(\dfrac{71}{210}\) (t/m)
+) Nếu \(4-7x< 0\Rightarrow x>\dfrac{4}{7}\)
Pt (*) \(\Leftrightarrow-4+7x=\dfrac{49}{30}\)
x = \(\dfrac{169}{210}\) (t/m)
Vậy x=\(\dfrac{71}{210}\) hoặc x = \(\dfrac{169}{210}\)
\(3x^3-48x=0\)
\(3x\cdot\left(x^2-16\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x=0\\x^2-16=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=\left\{\pm4\right\}\end{cases}}\)
Vậy,............