Б) х+3>0 или 4-х>0 или х-2.0
х>-3 или -х>-4 или х>2
х>4
= (2*5)^6 - (3*5)^5 = = (2^6)(5^6)-(3^5)(5^5)=
(5^5)(5*2^6-3^5)=(5^5)(320-243)=(5^6)(320-243)=
(5^5)77=(5^5)*11*7
простые делители: 1,5,7.
( X - 5 )*( X - 3 ) = 0
X^2 - 3X - 5X + 15 = 0
X^2 - 8X + 15 = 0
Y-3=0
Y=0+3
Y= 3.
Х+3=4
Х=4-3
Х=1
1+3=4
Cos(a-π/6)*cos(a+π/6)=1/2(cos(a-π/6-a-π/6)+cos(a-π/6+a+π/6))=
=1/2(cos(-π/3)+cos2a)=1/2*cosπ/3+1/2cos2a=1/2*1/2+1/2*cos2a=
=1/4+1/2*cos2a