cos 2x•cosx - sin2x•sinx = 0
cos2x•cosx - 2cosx•sin²x = 0
cosx(cos2x-2sin²x)= 0
cosx(cos2x-1+cos2x)= 0
cosx(2cos2x-1) = 0
1)cos x = 0
x = π/2 + πn, n€Z
2)2cos2x = 1
cos2x = 1/2
2x = ±π/3 + 2πk
x = ±π/6 + πk, k€Z
Log₃(7-2x)=2
7-2x>0
2x<7
x<3,5
log₃(7-2x)=log₃9
7-2x=9
2x=7-9
2x=-2
x=-1 (принадлежит интервалу области определения (-∞;3,5)
Ответ:-1
8. 4√2-3√8+2√32=4√2-2√4×2+2√16×2=4√2-6√2+16√2=14√2
A1= 5
a2=2/5
a3= 2 * 5/2 = 5
a4=2/5
a5=5
a6=2/5