4n(5n-a)+10(5n-a)= 2(2n+5)(5n-a)
3.
1)y=9x^2-3x+5 y'=18x-3
2)y=-2x^3+7x-1 y'=-6x^2+7
3)y=1/3x^12-2/7x-п y'=4x^11-2/7