Question

Rút gọn biểu thức:

A=\(2x\left(x-2\right)-x\left(2x-3\right)\)

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

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

D=\(\left(12x-3\right)\left(x+4\right)-x\left(2x+7\right)\)

E=\(\left(2x+y\right)\left(4x^2-2xy+y^2\right)\)

Answer 1

B = (x-1)(2x+1) - (x²-2x-1)

B = 2x²+x-2x-1-x²-2x-1 = x²-3x-2

B = x²+x-4x-2 = x(x+1) - 4(x+1)

B = (x+1)(x-4)

Answer 2

\(A=2x\left(x-2\right)-x\left(2x-3\right)\\ =2x^2-4x-2x^2+3x\\ =-x\\ B=\left(x-1\right)\left(2x+1\right)-\left(x^2-2x-1\right)\\ =x\left(2x+1\right)-\left(2x+1\right)-x^2+2x+1\\ =2x^2+x-2x-1-x^2+2x+1\\ =x^2+x\\ C=\left(x+y\right)\left(x^2-xy+y^2\right)-x^3\\ =x\left(x^2-xy+y^2\right)+y\left(x^2-xy+y^2\right)-x^3\\ =x^3-x^2y+xy^2+x^2y-xy^2+y^3-x^3\\ =y^3\)

\(D=\left(12x-3\right)\left(x+4\right)-x\left(2x+7\right)\\ =x\left(12x-3\right)+4\left(12x-3\right)-2x^2-7x\\ =12x^2-3x+48x-12-2x^2-7x\\ =10x^2+38x-12\\ E=\left(2x+y\right)\left(4x^2-2xy+y^2\right)\\ =2x\left(4x^2-2xy+y^2\right)+y\left(4x^2-2xy+y^2\right)\\ =8x^3-4x^2y+2xy^2+4x^2y-2xy^2+y^3\\ =8x^3+y^3\)

Answer 3

A= 2x² - 4x - 2x² + 3x = -x B= 2x² + x - 2x -1 -x² + 2x +1 = x² + x = x[ x + 1 ]

Answer 4

C = (x+y)(x² - xy + y²) - x³ = x³+y³-x³

C = y³

Answer 5

D =

Answer 6

E =

Answer 7

le thi hong van help!!!!!!!!!