Question

Phân tích đa thức sau thành nhân tử ( bằng cách tạo ra hằng đẳng thức)

x² + 3x - 10

 

Answer 1

\(x^2+3x-10\)

\(=x^2+5x-2x-10\)

\(=\left(x^2+5x\right)-\left(2x+10\right)\)

\(=x\left(x+5\right)-2\left(x+5\right)\)

\(=\left(x-2\right)\left(x+5\right)\)

Answer 2

Thích hđt thì chiều :))

x² + 3x - 10

= ( x² + 3x + 9/4 ) - 49/4

= ( x + 3/2 )² - ( 7/2 )²

= ( x + 3/2 - 7/2 )( x + 3/2 + 7/2 )

= ( x - 2 )( x + 5 )

Answer 3

\(x^2+3x-10\)   

\(=x^2+2\cdot x\cdot\frac{3}{2}+\left(\frac{3}{2}\right)^2-10-\left(\frac{3}{2}\right)^2\)   

\(=\left(x+\frac{3}{2}\right)^2-\frac{49}{4}\)   

\(=\left(x+\frac{3}{2}\right)^2-\left(\frac{7}{2}\right)^2\)   

\(=\left(x+\frac{3}{2}-\frac{7}{2}\right)\cdot\left(x+\frac{3}{2}+\frac{7}{2}\right)\)   

\(=\left(x+5\right)\cdot\left(x-2\right)\)