Question

[Bùi Ngọc Diệp]

Rút gọn các biểu thức sau:

a) 2x(2x-1)^2-3x(x+3)-4x(x+1)

b)(3x+1) (3^2+1) (3^4+1).....(3^100+1)

c) 5x(x^2-x)-x^2(5x-5) -15

d) (x+5)^2 - 4x(2x+3)^2 - (2x-1) (x+3) (x-3)

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(=2x\left(4x^2-4x+1\right)-3x^2-9x-4x^2-4x\)

\(=8x^3-8x^2+2x-7x^2-13x\)

\(=8x^3-15x^2-11x\)

c: \(=5x^3-5x^2-5x^3+5x^2-15=-15\)

d: \(=x^2+10x+25-4x\left(4x^2+12x+9\right)-\left(2x-1\right)\left(x^2-9\right)\)

\(=x^2+10x+25-16x^3-48x^2-36x-\left(2x-1\right)\left(x^2-9\right)\)

\(=-16x^3-47x^2-26x+25-2x^3+18x+x^2-9\)

\(=-18x^3-46x^2-8x+16\)