3*4-2-1:2:5=12-3:2:5=21:2:5=21:10=2.1
кос105=0.26
кос75=0.26
<span>cos 105-cos75= 0</span>
Х² + px + q = 0
D - дискриминант ( p² -4q)
x₁ =( -p +√D)/2 и х ₂= (-p - √D)/2
x₁ + x₂ = ( -p +√D)/2 + (-p - √D)/2 = (-p + √D -p - √D)/2 = -2p/2 = -p
x₁ * x₂ = ( -p +√D)/2 * (-p - √D)/2= ( p² - D)/4 = (p² - (p² - 4q))/4 = q
)(х+3)\2(х^2+6х+9)=(х-3)(х+3)\2(х+3)^2.=х-3\2х+6