Thực hiện phép tính
1. 4y^2/11x^4*(-3x^2/8y)
2. 4x^2/5y^2:6x/5y:2x/3y
3. x^2-4/3x+12*x+4/2x-4
4. x^2-36/2x+10*3/6-x
5. x^2-9y^2/x^2y^2*3xy/2x-6y
6. 3x^2-3y^2/5xy*15x^2y/2y-2x
7. 2a^3-2b^3/3a+3b*6a+6b/x^2-2ab+b^2
2. 4x^2/5y^2:6x/5y:2x/3y
3. x^2-4/3x+12*x+4/2x-4
4. x^2-36/2x+10*3/6-x
5. x^2-9y^2/x^2y^2*3xy/2x-6y
6. 3x^2-3y^2/5xy*15x^2y/2y-2x
7. 2a^3-2b^3/3a+3b*6a+6b/x^2-2ab+b^2