X^2 - 3x - 18 = 0
D = 9 + 4*18 = 81 = 9^2
x1 = (3 + 9)/2 = 12/2 = 6
x2 = (3 - 9)/2 = - 6/2 = - 3
1)=(a^2-b^2)/ab÷(b+a)/ab=(a-b)(a+b)/ab×ab/a+b=a-b
№ 3
должно быть по моему так
Y=2sin^2 2x
y'=2*2sin 2x *(sin2x)'=4sin 2x *cos 2x *(2x)'=8sin 2x cos 2x=4sin 4x
=(x² -x-3x+3)(x+4) - (x² +x+3x+3)(x-4) =
= (x² -4x+3)(x+4) - (x² +4x+3)(x-4)=
=x³ -4x² +3x+4x² -16x+12 - (x³ +4x² +3x-4x² -16x-12)=
= x³ -13x+12 -x³ +13x +12 = 24