(x-1)³=27

(x-1)³=3³

^x-1=3

^=>x=3+1=4

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

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

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

\(5x=5\)

\(x=1\)

b) \(2x^3\left(2x-3\right)-x^2\left(4x^2-6x+2\right)=0\)

\(4x^4-6x^3-4x^4+6x^2-2x^2=0\)

\(-2x^2=0\)

\(x^2=0\)

\(x=0\)

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

\(=x^5+x^4+x^3-x^4-x^3-x^2+x^2+x+1\)

\(=x^5+x+1\)

a) 2x(3x^2 -5x + 3) = 6x^3 - 10x^2 + 6x

b) -2x(x^2 +5x-3) = -2x^3 - 10x^2 + 6x 

c) 2 dấu trừ liền nhau??

bài 2: 

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

b) \(-\left(5x-4\right)\left(2x+3\right)=-\left(10x^2-8x+15x-12\right)=-10x^2-7x+12\)

c) \(\left(2x-y\right)\left(4x^2-2xy+y^2\right)=8x^3-4x^2y-4x^2y+2xy^2+2xy^2-y^3=8x^3-8x^2y+2xy^2-y^3\)

d) \(\left(3x-4\right)\left(x+4\right)+\left(5-x\right)\left(2x^2+3x-1\right)=3x^2+8x-16+10x^2-2x^3+15x-3x^2-5+x=10x^2+24x-21\)

e) \(7x\left(x-4\right)-\left(7x+3\right)\left(2x^2-x+4\right)=7x^2-28x-\left(14x^3+6x^2-7x^2-3x+28x+12\right)=-14x^2+8x^2-53x-12\)

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

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

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

a) \(x^3-9x^2+15x+25\)

\(=x^3+x^2-10x^2-10x+25x+25\)

\(=x^2\left(x+1\right)-10x\left(x+1\right)+25\left(x+1\right)\)

\(=\left(x+1\right)\left(x^2-2.x.5+25\right)=\left(x+1\right)\left(x-5\right)^2\)

b) \(x^8-4x^2-11x+30:\text{đề sai thì phải bạn ạ!}\)

c) \(x^4+x^3-22x^2+15x-36\)

\(=\left(2x^4-6x^3\right)+\left(7x^3-21x^2\right)-\left(x^2-3x\right)+12x-36\)

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

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

\(=\left(x-3\right)\left[\left(2x^3+8x^2\right)-\left(x^2+4x\right)+3\left(x+4\right)\right]\)

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

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