(х-2у)^2=х^2-4ху+4у^2
(1.4м-н)(1.4м+н)=1.96м^2-н^2
36а^2-б^2=(6а-б)(6а+б)
4-4с+с^2=4-2с-2с+с^2=(4-2с)-(2с-с^2)=
=2(2-с)-с(2-с)=(2-с)(2-с)=(2-с)^2
15у^3-3у^3=12у^3
49-(х+5)^2=0
49-х^2-10х-25=0
-х^2-10х+24=0
х^2+10х-24=0
Д=100-4×1×(-24)=196
х1=(-10-14)/2=-12
х2=(-10+14)/2=2
Cos8x=cos²4x-sin²4x=1-2sin²4x ⇒ 1-2sin²4x=sin4x, получили кв ур-ние:2sin²4x+sin4x-1=0 ⇒ sin4x=-1 (4x=-π/2+2πk ⇒ x1=-π/8+πk/2) u sin4x=1/2(4x=(π/2+-π/6)+2πk ⇒ x=(π/8+-π/24)+πk/2)
(x+y³)²=x²+2xy³+y⁶; (m²+n²)²=m⁴+2m²n²+n⁴;
(ab+c)²=a²b²+2abc+c²; (x+yz)²=x²+2xyz+y²z²;
(2p+3q²)²=4p²+2·2·3pq²+9q⁴=4p²+12pq²+9q⁴; (3ab²+2c³)²=9a²b⁴+12ab²c³+c⁶;
D = b²-4ac = 16-4*1*3 = 4.
x(1) = (-4+2)/2 = -1.
x(2) = (-4-2)/2 = -3.
---(+)---(-3)---(-)---(-1)----(+)--→x
ответ : х принадлежит
(-оо;-3) U (-1;+oo).