Question

bài 1 thực hiện phép tính

a) (-2x³)(x²+5x-1/2)

b) (6x³-7x²-x+2):(2x+1)

bài 2 phân tích đa thức thành nhân tử

a) 9x(3x-y)+3y(y-3x)

b) x³-3x²-9x+27

giải hộ mim gấp nhé mai mik phải nộp bài này rồi cảm ơn các bạn

Answer 1

1.

a) \(\left(-2x^3\right)\)\(\left(x^2+5x-\frac{1}{2}\right)\) = \(-2x^5\)\(-10x^4\) \(+x^3\)

b) (\(6x^3-7x^2\)\(-x+2\))\(:\left(2x+1\right)\)=\(3x^2-5x+2\)

2.

a) 9x(3x-y) + 3y (y-3x)=9x(3x-y)-3y(3x-y)

= (9x-3y)(3x-y)

= 3(3x-y)(3x-y)

= 3(3x-y)^2

b) \(x^3-3x^2\)\(-9x+27\)= \(\left(x^3-3x^2\right)\)\(-\left(9x-27\right)\)

= \(x^2\left(x-3\right)\)\(-9\left(x-3\right)\)

= \(\left(x^2-9\right)\left(x-3\right)\)

= \(\left(x+3\right)\left(x-3\right)\left(x-3\right)\)

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

Answer 2

Bài 1 ) a ) \(\left(-2x^3\right)\left(x^2+5x-\frac{1}{2}\right)\)

\(=-2x^5-10x^4+x^3\)

b ) \(\left(6x^3-7x^2+x+2\right):\left(2x+1\right)\)

\(=3x^2-5x+2\)

2 ) a ) \(9x\left(3x-y\right)+3y\left(y-3x\right)\)

\(=9x\left(3x-y\right)-3y\left(3x-y\right)\)

\(=\left(3x-y\right)\left(9x-3y\right)\)

\(=3\left(3x-y\right)\left(x-y\right)\)

b ) \(x^3-3x^2-9x+27\)

\(=\left(x^3-3x^2\right)-\left(9x-27\right)\)

\(=x^2\left(x-3\right)-9\left(x-3\right)\)

\(=\left(x^2-9\right)\left(x-3\right)\)

\(=\left(x-3\right)\left(x+3\right)\left(x-3\right)\)