Question

1. Phân tích đa thức thành nhân tử :
a) x³+2x²+x
b) 25-x²+4xy-4y²
2. Tìm x, biết: 
-2x²-4x+6=0

 

Answer 1

1:

a) \(x^3+2x^2+x=x\left(x^2+2x+1\right)=x\left(x+1\right)^2\)

b) \(25-x^2+4xy-4y^2=25-\left(x-2y\right)^2=\left(5-x+2y\right)\left(5+x-2y\right)\)

2

\(-2x^2-4x+6=0\)

\(\Leftrightarrow-2\left(x^2+2x-3\right)=0\)

\(\Leftrightarrow x^2-x+3x-3=0\)

\(\Leftrightarrow x\left(x-1\right)+3\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x+3\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x-1=0\\x+3=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=1\\x=-3\end{array}\right.\)

Answer 2

1,

a) x( x² + 2x +1) = x(x+1)²

b)25 - (x-2y)² = (5-x+2y)(5+x-2y)

2,

(x-1)(x+3)=0

<=>x=1 hoặc x=-3

 

Answer 3

1.a)x^3+2x^2+x=x(x^2+2x+1)

=x(x+1)^2

b)25-x^2+4xy-4y^2=25-(x^2-4xy+