3x(m-5x)=3mx- 15x^2=6x^2y^3+n
So:
3Mx=6x^2y^3
- 15x^2=N
So m = 6x 2y 3/(3x) = 2xy 3, n =- 15x 2.
4、
(1) in brackets = (-8a3+10a2+6a)/(-2a) = 4a2-5a-3.
(2) In brackets = (-4x3Y2+4x2Y2-6xy)/(2x2y-2xy+3)
=[(-2xy)*(2x^2y-2xy+3)]/(2x^2y-2xy+3)
=-2xy
5、
(x^2+ax+5)(-6x^3)
=-6x^5-6ax^4-30x^3
Because it does not contain x 4.
So, -6a=0.
So, a=0