Ответ:
решу на листочке)))) 5 мминут
1) (2a+3b)^3= 8a^3+3*(4a^2*3b)+3*(2a*9b^2)+27b^3=8a^3+36a^2*b+64ab^2+27b^3;
2) (2y+5)^3= 8y^3+3*(4y^2*5)+3*(2y*25)+125= 8y^3+60y^2+150y+125;
3) (3m-4n)^3= 27m^3-3*(9m^2*4n)+3*(3m*16n^2)-64n^3= 27m^3-108m^2*n+144mn^2-64n^3.
(2sina - 2cosa)^2 = 1
4sin^2a - 4*2sinacosa + 4cos^2a = 1
4 - 4*sin2a = 1
- 4sin2a = - 3
sin2a = 3/4
sin2a = 0,75
Cos45° * Sin3105° + 1/2ctg(- 315°) - Cos270° = Cos45° * Sin(360° * 8 + 225°) -
- 1/2ctg(90° *2 + 135°) - Cos270°= Cos45° * Sin225° - 1/2ctg(90°+45°) - Cos270° =
= Cos45° * Sin(180° + 45°) + 1/2tg45° - Cos270° = - Cos45° * Sin45° +
+ 1/2 tg45° - Cos270° = - √2/2 * √2/2 + 1/2 * 1 - 0 = - 1/2 + 1/2 = 0
6ab-36a^2+b^2-6ab=b^2-36a^2
x^2-16x+64-4x^2+16x=64-3x^2