phân tích đa thức thành nhân tử : x^4+6x^3+7x^2-6x+1
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x^4+6x^3+7x^2–6x+1
=x^4+(6x^3–2x^2)+(9x^2–6x+1)
= x^4+2x^2(3x–1)+(3x–1)^2
=(x^2+3x–1)^2
\(x^4-6x^3+7x^2-6x+1\)
\(=x^4+x^2+1-6x^3+6x^2-6x\)
\(=\left(x^2+1\right)^2-x^2-6x\left(x^2-x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2-x+1\right)-6x\left(x^2-x+1\right)\)
\(=\left(x^2-x+1\right)\left(x^2+x+1-6x\right)\)
\(=\left(x^2-x+1\right)\left(x^2-5x+1\right)\)
= x4 - x3 + x2 - 5x3 + 5x2 - 5x + x2 - x +1 = x2 ( x2 - x +1 ) - 5x ( x2 - x +1 ) + x2 - x +1 = ( x2 - x +1 ) ( x2 - 5x + 1 )
x4+6x3+7x2-6x+1
=(x4-2x2+1)+(6x3-6x)+9x2
=(x2-1)2+6x(x2-1)+9x2
=(x2-1).(x2-1+6x)+9x2
=(x2+3x-1)2
x4+6x3+7x2-6x+1
=(x4-2x2+1)+(6x3-6x)+9x2
=(x2-1)2+6x(x2-1)+9x2
=(x2-1). (x2-1+6x)+9x2
=(x2+3x-1)2
A=x^4+6x^3+7x^2–6x+1=x^4+(6x^3–2x^2)+(9x^2–6x+1)
= x^4+2x^2(3x–1)+(3x–1)^2 =(x^2+3x–1)^2
chỉnh lại tí
Đặt P(x)=x4+6x3+7x2- 6x+1
Đặt y=x2-1
=>y2=x4-2x2+1
P(x)=x4-2x2+1+6x3-6x+9x2
=(x2-1)2+6x(x2-1)+9x2
Q(y)=y2+6xy+9x2
=(y+3x)2
P(x)=(x2-1+3x)2
TỰ LÀM NHÉ !
.c1: F(x) = x^4 + (6x^3 - 2x^2) + 9x^2 - 6x +1)
= x^4 + 2x^2(3x-1)+(3x-1)^2
= (x^2 +3x-1)^2
C2:giả sử x khác 0, ta có:
F(x) = x^2(x^2 +6x+7-6/x+1/2^2)
= x^2 [ ( x^2 +1/2^2 +6(x-1/2)+7]
đặt x-1/x = y, suy ra : x^2 +1/x^2 = y^2 +2. do đó đa thức trở thành:
F(x;y) = x^2(y^2+2+6y+7)
= x^2(y+3)^3
=(xy+3x)^3
=[x(x-1/x)+3x]^2
=(x^2+3x-1)^2
xét \(x\ne0\)ta có :
\(M=\)\(^{x^2\cdot\left(x^2+6x+7-\frac{6}{x}+\frac{1}{x^2}\right)}\)
Đặt \(x-\frac{1}{x}=t\Rightarrow t^2=x^2-2+\frac{1}{x^2}\Leftrightarrow t^2+2=x^2+\frac{1}{x^2}\)
Do đó \(M=x^2\cdot\left(t^2+2+6t+7\right)\Leftrightarrow x^2\cdot\left(t^2+6t+9\right)\)
\(\Leftrightarrow M=x^2\cdot\left(t+3\right)^2\)
M=\(x^4+3x^3-x^2+3x^3+9x^2-3x-x^2-3x+1\)
\(=x^2(x^2+3x-1)+3x\left(x^2+3x-1\right)-\left(x^2+3x-1\right)\)
\(=\left(x^2+3x-1\right)^2\)
Ta có: \(P\left(x\right)=x^4+6x^3+7x^2-6x+1\)
\(=x^4+\left(6x^3-2x^2\right)+\left(9x^2-6x+1\right)\)
\(=x^4+2x^2\left(3x-1\right)+\left(3x-1\right)^2\)
\(=\left(x^2+3x-1\right)^2\)
\(x^4+6x^3+7x^2-6x+1\)
\(=x^4+6x^3+9x^2-2x^2-6x+1\)
\(=\left(x^2\right)^2+2.x^2.3x+\left(3x\right)^2-2\left(x^2+3x\right)+1\)
\(=\left(x^2+3x\right)^2-2\left(x^2+3x\right).1+1^2\)
\(=\left(x^2+3x-1\right)^2\)
Chúc bạn học tốt.
\(x^4+6x^3+7x^2-6x+1\)
\(=x^4+6x^3+9x^2-2x^2-6x+1\)
\(=x^2\left(x+3\right)^2-2\left(x^2+3x\right)+1\)
\(=\left(x^2+3x\right)^2-2\left(x^2+3x\right)+1=\left(x^2+3x-1\right)^2\)