Phân tích đa thức thành nhân tử : –4x2 + 8x – 3
Phân tích đa thức thành nhân tử : (x2 + x)2 + 4x2 + 4x – 12
\(\left(x^2+x\right)^2+4x^2+4x-12=\left[\left(x^2+x\right)^2+4\left(x^2+x\right)+4\right]-16=\left(x^2+x+2\right)-4^2=\left(x^2+x+2-4\right)\left(x^2+x+2+4\right)=\left(x^2+x-2\right)\left(x^2+x+6\right)=\left(x-1\right)\left(x+2\right)\left(x^2+x+6\right)\)
\(\left(x^2+x\right)^2+4x^2+4x-12\\ =\left(x^2+x+2\right)-4\\ =\left(x^2+x-2\right)\left(x^2+x+6\right)\)
\(\left(x^2+x\right)^2+4x^2+4x-12\)
\(=\left(x^2+x+6\right)\left(x^2+x-2\right)\)
\(=\left(x^2+x+6\right)\left(x+2\right)\left(x-1\right)\)
Phân tích đa thức thành nhân tử :
1) x^2 – 2x – 24
2) x^2 – 8x + 15
3) x^2 – 9x + 14
4) x^2 – 3x – 15
1: \(x^2-2x-24=\left(x-6\right)\left(x+4\right)\)
2: \(x^2-8x+15=\left(x-3\right)\left(x-5\right)\)
3: \(x^2-9x+14=\left(x-2\right)\left(x-7\right)\)
Phân tích đa thức sau thành nhân tử : xn + 3 + xn
\(x^{n+3}+x^n=x^n.x^3+x^n=x^n\left(x^3+1\right)=x^n\left(x+1\right)\left(x^2-x+1\right)\)
\(x^{n+3}+x^n=x^n\left(x^3+1\right)=x^n\left(x+1\right)\left(x^2-x+1\right)\)
\(x^{n+3}+x^n=x^n\left(x^3+1\right)=x^n\cdot\left(x+1\right)\left(x^2-x+1\right)\)
phân tích đa thức thành nhân tử
a)x^4-4x^3+3x^2+8x-10=0
b)x^4-3x^2-10x-4=0
Phân tích đa thức thành nhân tử : (x2 + 6x + 9)3 - y6
\(=\left(x+3\right)^6-y^6\\ =\left[\left(x+3\right)^3-y^3\right]\left[\left(x+3\right)^3+y^3\right]\\ =\left(x+3-y\right)\left[\left(x+3\right)^2+y\left(x+3\right)+y^2\right]\left(x+3+y\right)\left[\left(x+3\right)^2-y\left(x+3\right)+y^2\right]\\ =\left(x+y+3\right)\left(x-y+3\right)\left(x^2+6x+9+xy+3y+y^2\right)\left(x^2+6x+9-xy-3y+y^2\right)\)
\(\left(x^2+6x+9\right)^3-\left(y^2\right)^3=\left(x^2+6x+9-y^2\right)\left[\left(x^2+6x+9\right)^2+\left(x^2+6x+9\right)y^2+y^4\right]\)
\(=\left[\left(x+3\right)^2-y^2\right]\left\{\left[\left(x^2+6x+9\right)^2+2\left(x^2+6x+9\right)y^2+y^4\right]-\left(x^2+6x+9\right)y^2\right\}\)
\(=\left(x+3-y\right)\left(x+3+y\right)\left[\left(x^2+6x+9+y^2\right)^2-\left(x+3\right)^2y^2\right]\)
\(=\left(x+3-y\right)\left(x+3+y\right)\left[\left(x^2+6x+9+y^2\right)-\left(x+3\right)y\right]\left(x^2+6x+9+y^2\right)+\left(x+3\right)y\)
\(=\left(x+3-y\right)\left(x+3+y\right)\left(x^2+6x+9+y^2-xy-3y\right)\left(x^2+6x+9+y^2+xy+3y\right)\)
Phân tích đa thức thức thành nhân tử : (x – 5)(x – 1)(x + 3)(x + 7) + 60
\(\left(x-5\right)\left(x-1\right)\left(x+3\right)\left(x+7\right)+60\)
\(=\left(x^2+2x-35\right)\left(x^2+2x-3\right)+60\)
\(=\left(x^2+2x\right)^2-38\left(x^2+2x\right)+105+60\)
\(=\left(x^2+2x\right)^2-3\left(x^2+2x\right)-35\left(x^2+2x\right)+165\)
\(=\left(x^2+2x-3\right)\left(x^2+2x-35\right)\)
\(=\left(x+3\right)\left(x-1\right)\left(x+7\right)\left(x-5\right)\)
Phân tích đa thức thành nhân tử : xm + 4 – xm + 3 – x + 1
\(x^{m+4}-x^{m+3}-x+1=x^{m+3}\left(x-1\right)-\left(x-1\right)=\left(x-1\right)\left(x^{m+3}-1\right)\)
Ta có: \(x^{m+4}-x^{m+3}-x+1\)
\(=x^{m+3}\left(x-1\right)-\left(x-1\right)\)
\(=\left(x-1\right)\left(x^{m+3}-1\right)\)
Phân tích đa thức thành nhân tử : x^4 – x^3 – x + 1
\(x^4-x^3-x+1=\left(x^4-x^3\right)-\left(x-1\right)=x^3\left(x-1\right)-\left(x-1\right)=\left(x^3-1\right)\left(x-1\right)=\left(x-1\right)^2.\left(x^2+x+1\right)\)
x4 - x3 - x + 1
= (x4 - x3) - (x - 1)
= x3(x - 1) - (x - 1)
= (x3 - 1)(x - 1)
Phân tích đa thức thành nhân tử : x^4 - 2x^3 + 2x - 1
\(x^4-2x^3+2x-1=x^3\left(x-1\right)-x^2\left(x-1\right)-x\left(x-1\right)+\left(x-1\right)=\left(x-1\right)\left(x^3-x^2-x+1\right)=\left(x-1\right)\left[x^2\left(x-1\right)-\left(x-1\right)\right]=\left(x-1\right)^2\left(x^2-1\right)=\left(x-1\right)^3\left(x+1\right)\)
\(x^4-2x^3+2x-1\)
\(=\left(x^2-1\right)\left(x^2+1\right)-2x\left(x^2-1\right)\)
\(=\left(x-1\right)^3\cdot\left(x+1\right)\)