\(1.5x\left(x^2+2x-1\right)-3x^2\left(x-2\right)=5x^3+10x^2-5x-3x^3+6x^2\)

                                                                  \(=2x^3+16x^2-5x\)

                                                                  \(=\left(2x^3-x\right)+\left(16x^2-4x\right)\)

                                                                  \(=x\left(2x^2-1\right)+4x\left(4x-1\right)\left(ĐCCM\right)\)

1: \(F=\left(\dfrac{-1}{2}-2\right)^3-\left(-\dfrac{1}{2}+3\right)^3+\left(-2+\dfrac{3}{2}\right)^3+\left(-\dfrac{1}{2}+1\right)^2\)

\(=\dfrac{-125}{8}-\dfrac{125}{8}+\dfrac{-1}{8}+\dfrac{1}{4}\)

\(=\dfrac{-251}{8}+\dfrac{1}{4}=\dfrac{-249}{8}\)

2:\(N=\left(-1-1\right)^2-\left(-1+\dfrac{1}{8}\right)+\left(-1+1\right)^3\)

=4+1-1/8

=5-1/8=39/8

a) \(\left(x+3\right)\left(x+4\right)\left(x+5\right)\left(x+6\right)+1\)

\(=\left(x^2+9x+18\right)\left(x^2+9x+20\right)+1\)

\(=\left(x^2+9x+19\right)^2-1+1\)

\(=\left(x^2+9x+19\right)^2\)

b) \(x^2+y^2+2x+2y+2\left(x+1\right)\left(y+1\right)+2\)

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

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

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

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

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

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

\(\left(x-y-2\right)^2\)

d) \(x^2+2x\left(y+1\right)+y^2+2y+1\)

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

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

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

1) \(5xy^2\left(x-1\right)-3y\left(x^2-x\right)\)

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

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

\(=xy\left(x-1\right)\left(5y-3\right)\)

\(1)\)\(5xy^2\left(x-1\right)-3y\left(x^2-x\right)\)

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

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

\(=\)\(xy\left(x-1\right)\left(5y-3\right)\)

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

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

\(=\)\(\left(x+y\right)\left(x-1+x+y\right)\)

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

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

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

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

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

Chúc bạn học tốt ~ 

1a : x = -1

2a : x = 10

còn mấy bài khác mình không biết giải nha

1. \(125x^3+y^6=\left(5x\right)^3+\left(y^2\right)^3\)

\(=\left(5x+y^2\right)\left[\left(5x\right)^2-5x.y^2+\left(y^2\right)^2\right]\)

\(=\left(5x+y^2\right)\left(25x^2-5xy^2+y^4\right)\)

2. \(4x\left(x-2y\right)+8y\left(2y-x\right)\)

\(=4x\left(x-2y\right)-8y\left(x-2y\right)\)

\(=\left(x-2y\right)\left(4x-8y\right)\)

3. \(25\left(x-y\right)^2-16\left(x+y\right)^2\)

\(=\left[5\left(x-y\right)\right]^2-\left[4\left(x+y\right)\right]^2\)

\(=\left[5\left(x-y\right)-4\left(x+y\right)\right]\left[5\left(x-y\right)+4\left(x+y\right)\right]\)

\(=\left(5x-5y-4x-4y\right)\left(5x-5y+4x+4y\right)\)

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

4. \(x^4-x^3-x^2+1\)

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

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

\(=\left(x-1\right)\left(x^3-x-1\right)\)

5. \(a^3x-ab+b-x\)

\(=a^3x-x-ab+b\)

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

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

\(=\left(a-1\right)\left[x\left(a^2+a+1\right)-b\right]\)

6. \(x^3-64=x^3-4^3\)

\(=\left(x-4\right)\left(x^2+4x+16\right)\)

7. \(0,125\left(a+1\right)^3-1\)

\(=\left[0,5\left(a+1\right)\right]^3-1^3\)

\(=\left[0,5\left(a+1\right)-1\right]\left\{\left[0,5\left(a+1\right)\right]^2+\left[0,5\left(a+1\right).1\right]+1^2\right\}\)

\(=\left[0,5\left(a+1-2\right)\right]\left[0,25a^2+0,5a+0,25+0,5a+0,5+1\right]\)

\(=\left[0,5\left(a-1\right)\right]\left(0,25a^2+a+1,75\right)\)

8. \(9\left(x+5\right)^2-\left(x-7\right)^2\)

\(=\left[3\left(x+5\right)\right]^2-\left(x-7\right)^2\)

\(=\left(3x+15-x+7\right)\left(3x+15+x-7\right)\)

\(=\left(2x+22\right)\left(4x+8\right)\)

9. \(49\left(y-4\right)^2-9\left(y+2\right)^2\)

\(=\left[7\left(y-4\right)\right]^2-\left[3\left(y+2\right)\right]^2\)

\(=\left(7y-28-3y-6\right)\left(7y-28+3y+6\right)\)

\(=\left(4y-34\right)\left(10y-22\right)\)

10. \(x^2y+xy^2-x-y=xy\left(x+y\right)-\left(x+y\right)\)

\(=\left(x+y\right)\left(xy-1\right)\)

11. \(x^3+3x^2+3x+1-27z^3\)

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

\(=\left(x+1-3z\right)\left(x^2+2x+1+3xz+3z+9z^2\right)\)

12. \(x^2-y^2-x+y=\left(x-y\right)\left(x+y\right)-\left(x-y\right)\)

\(=\left(x-y\right)\left(x+y-1\right)\)