phân tích 4x^4 16
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\(4x^4-16-4x^2-16x\)
\(=4x^2\left(x^2-1\right)-16\left(1+x\right)\)
\(=4x^2\left(x+1\right)\left(x-1\right)-16\left(x+1\right)\)
\(=\left(x+1\right)\left[4x^2\left(x-1\right)-16\right]\)
\(=\left(x+1\right)4\left[x^2\left(x-1\right)-4\right]\)
Nguyễn Văn Tuấn AnhNs r, không biết thì not làm
\(4x^4-16-4x^2-16x\)
\(=4x^2\left(x^2-1\right)-16\left(x+1\right)\)
\(=4x^2\left(x-1\right)\left(x+1\right)-16\left(x+1\right)\)
\(=\left(x+1\right)\left[4x^2\left(x-1\right)-16\right]\)
\(=4\left(x+1\right)\left[x^2\left(x-1\right)-4\right]\)
\(=4\left(x+1\right)\left[x^3-x^2-4\right]\)
\(=4\left(x+1\right)\left[x^3+x^2+2x-2x^2-2x-4\right]\)
\(=4\left(x+1\right)\left[x\left(x^2+x+2\right)-2\left(x^2+x+2\right)\right]\)
\(=4\left(x+1\right)\left(x-2\right)\left(x^2+x+2\right)\)
\(16-x^2\)
\(=\left(4-x\right)\left(4+x\right)\)
\(---\)
\(16-3x+1^2\) (kt lại đề bài nhé)
\(x^4y^4+4x^2y^2+4\)
\(=\left[\left(xy\right)^2\right]^2+2\cdot\left(xy\right)^2\cdot2+2^2\)
\(=\left[\left(xy\right)^2+2\right]^2=\left(x^2y^2+2\right)^2\)
\(---\)
\(y^2-4y+4-x^2\)
\(=y^2-2\cdot y\cdot2+2^2-x^2\)
\(=\left(y-2\right)^2-x^2\)
\(=\left(y-2-x\right)\left(y-2+x\right)\)
a) \(4x^4+4x^3-x^2-x=4x^3\left(x+1\right)-x\left(x+1\right)\)
\(=\left(4x^3-x\right)\left(x+1\right)=x\left(4x^2-1\right)\left(x+1\right)\)
\(=x\left\{\left(2x\right)^2-1\right\}\left(x+1\right)=x\left(2x-1\right)\left(2x+1\right) \left(x+1\right)\)
c) \(x^4-4x^3+8x^2-16x+16=x^4+8x^2+16-\left(4x^3+16x\right)\)
\(=\left(x^2+4\right)^2-4x\left(x^2+4\right)=\left(x^2-4x+4\right)\left(x^2+4\right)=\left(x-2\right)^2\left(x^2+4\right)\)
b) \(x^6-x^4-9x^3+9x^2=x^4\left(x^2-1\right)-\left(9x^3-9x^2\right)\)
\(=x^4\left(x-1\right)\left(x+1\right)-9x^2\left(x-1\right)\)
\(=\left(x^5+x^4-9x^2\right)\left(x-1\right)=\left(x-1\right)x^2\left(x^3+x^2-9\right)\)
\(x^4-4x^3+8x^2-16x+16 \)
\(=x^3\left(x-2\right)-2x^2\left(x-2\right)+4x\left(x-2\right)-8\left(x-2\right)\)
\(=\left(x-2\right)\left(x^3-2x^2+4x-8\right)\)
\(=\left(x-2\right)\left[x^2\left(x-2\right)+4\left(x-2\right)\right]\)
\(=\left(x-2\right)^2\left(x^2+4\right)\)
c: \(x^2-4+3\left(x-2\right)^2\)
\(=\left(x-2\right)\left(x+2\right)+\left(x-2\right)\left(3x-6\right)\)
\(=\left(x-2\right)\left(x+2+3x-6\right)\)
\(=\left(4x-4\right)\left(x-2\right)\)
\(=4\left(x-1\right)\left(x-2\right)\)
a,x4-4x3+8x2-16x+16
=x4-4x3+4x2+4x2-16x+16
=x2.(x-2)2+4.(x-2)2
=(x-2)2(x2+4)
3x4 - 8x3 + 16
Thử với x = 2 ta được :
3.24 - 8.23 + 16 = 0
Vậy x = 2 là nghiệm của đa thức . Theo hệ quả của định lí Bézout thì đa thức trên chia hết cho x - 2
Thực hiện phép chia 3x4 - 8x3 + 16 cho x - 2 ta được 3x3 - 2x2 - 4x - 8
=> 3x4 - 8x3 + 16 = ( x - 2 )( 3x3 - 2x2 - 4x - 8 )
Ta có : 3x3 - 2x2 - 4x - 8
= 3x3 + 4x2 + 4x - 6x2 - 8x - 8
= x( 3x2 + 4x + 4 ) - 2( 3x2 + 4x + 4 )
= ( x - 2 )( 3x2 + 4x + 4 )
Tổng kết : 3x4 - 8x3 + 16 = ( x - 2 )( x - 2 )( 3x2 + 4x + 4 ) = ( x - 2 )2( 3x2 + 4x + 4 )
Ta có: \(3x^4-8x^3+16=\left(3x^4-12x^3+12x^2\right)+\left(4x^3-16x^2+16x\right)+\left(4x^2-16x+16\right)\)
\(=3x^2.\left(x^2-4x+4\right)+4x.\left(x^2-4x+4\right)+4.\left(x^2-4x+4\right)\)
\(=\left(3x^3+4x+4\right)\left(x-2\right)^2\)
ta có
\(5x=-3y=4z\)
\(\Rightarrow\frac{x}{12}=-\frac{y}{20}=\frac{z}{15}\)
\(\Rightarrow\frac{x}{12}=-\frac{y}{20}=\frac{3z}{45}=\frac{x-y+3z}{12+20+45}=\frac{7}{77}=\frac{1}{11}\)
\(\Rightarrow\hept{\begin{cases}x=\frac{1}{11}.12=\frac{12}{11}\\-y=\frac{1}{11}.20=\frac{20}{11}\\3z=\frac{1}{11}.45=\frac{45}{11}\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=\frac{12}{11}\\y=-\frac{20}{11}\\z=\frac{45}{11}:3=\frac{15}{11}\end{cases}}\)
Vậy \(\hept{\begin{cases}x=\frac{12}{11}\\y=\frac{-20}{11}\\z=\frac{15}{11}\end{cases}}\)
\(\text{a) }4x^{16}+81=4x^4+36x^2+81-36x^8\)
\(=\left(4x^{16}+36x^8+81\right)-36x^8\)
\(=\left[\left(2x^8\right)^2+2.2x^8.9+9^2\right]+\left(6x^4\right)^2\)
\(=\left(2x^8+9\right)^2-\left(6x^4\right)^2\)
\(=\left(2x^8+9-6x^4\right)\left(2x^8+9+6x^4\right)\)
\(\text{b) }x^4+2018x^2+2017x+2018\)
\(=x^4+2018x^2+2018x-x+2018\)
\(=\left(x^4-x\right)+\left(2018x^2+2018x+2018\right)\)
\(=x\left(x^3-1\right)-2018\left(x^2+x+1\right)\)
\(=x\left(x-1\right)\left(x^2+x+1\right)+2018\left(x^2+x+1\right)\)
\(=\left(x^2-x\right)\left(x^2+x+1\right)+2018\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+2018\right)\)
sửa đề : \(4x^4+16=4x^4+2.\left(2x^2\right).4+16-16x^2\)
\(=\left(2x^2+4\right)^2-16x^2=\left(2x^2+4-4x\right)\left(2x^2+4+4x\right)\)