A) 3b(c-2x)
B) 3y(y-4)
C) 5x2y2(x-9y)
D) 3c(c3-4ac+2)
3х(4х-1)-2х(4х+5)=12х^2 - 3x -8x^2 -10x =4x^2-13x
(3+√5)²-5(3+√5)(3-√5)+(3-√5)² / (3+√5)+(3-√5)+2 =
= 9+6√5+5-45+25+9-6√5+5 / 3+√5+3-√5+2 = 8/8 = 1
5√3*√15/√5=5√3*√(15/5)=5√3*√3=5*3=15.
Ответ: 15.