Question

1: Làm tính nhân

a, 2x.(x2 -7x-3)

b, (−2x3+34y2−7xy).4xy2(−2x3+34y2−7xy).4xy2

c, ( x2 -2x+3).(x-4)

d , ( 2x3 - 3x-1).(5x+2)

2 phân tích các đa thức sau thành nhân tử :

a, x3 -2x2+x

b , x2−2x−15x2−2x−15

c , y(x-z)+7(z-x)

d, 36 - 12x + x2

Answer 1

Bài 2:

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

\(=x\left(x^2-2x+1\right)\)

\(=x\left(x-1\right)^2\)

b)\(x^2-2x-15\)

\(=x^2-5x+3x-15\)

\(=x\left(x-5\right)+3\left(x-5\right)\)

c)\(y\left(x-z\right)+7\left(z-x\right)\)

\(=7\left(z-x\right)-y\left(z-x\right)\)

\(=\left(7-y\right)\left(z-x\right)\)

\(=\left(x-5\right)\left(x+3\right)\)

d)\(36-12x+x^2\)

\(=x^2-12x+36\)

\(=\left(x-6\right)^2\)

Answer 2

Bài 1:

a)\(2x\left(x^2-7x-3\right)=2x^3-14x^2-6x\)

b)\(\left(-2x^3+34y^2-7xy\right)\cdot4xy^2=136xy^4-28x^2y^3-8x^4y^2\)

c)\(\left(x^2-2x+3\right)\left(x-4\right)\)

\(=x^2\left(x-4\right)-2x\left(x-4\right)+3\left(x-4\right)\)

\(=x^3-4x^2-2x^2+8x+3x-12\)

\(=x^3-6x^2+11x-12\)

d)\(\left(2x^3-3x-1\right)\left(5x+2\right)\)

\(=5x\left(2x^3-3x-1\right)+2\left(2x^3-3x-1\right)\)

\(=10x^4-15x^2-5x+4x^3-6x-2\)

\(=10x^4+4x^3-15x^2-11x-2\)