1)y`(x)=9x^2-4x-5
D=16+180=196
x1=4+14/18=1
x2=4-14/18=-0.(5)
Ответ: 1
3)-sinα/-sinα+2tgα*ctgα=1+2*sinα/cosα*cosα/sinα=1+2=3
12х+54-4х+8=72
8х=72-8-54
8х=10
х=1,25
cos(L+П/3)+cos(П/3-L)= cosLcosП/3 - sinLsinП/3 + cosП/3cosL + sinП/3sinL =
<span>-Cosx=-1/2
cosx=1/2
X=+-п/3+2пn,n принадл. Z
x=60 градусов
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