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
ctg x=1/tg x, tgx=t:
2t+2/t=5
2t^2-5t+2=0
D=25-4*2*2=9
t=(5+-3)/4
t=2 or t=1/2
tgx=2 or tgx=1/2
x=arctg2+pi*k, k in Integers OR x=arctg0.5 + pi*m, m in Integers
Y=6-x
(x-1)(4-x)=2
4x-x^2-4+x=2
-x^2+5x-6=0
d=b^2-4ac=25-24=1
x1=-4/-2=2
x2=-6/-2=3