X(4x-12)=0
x1=0 или 4x=12
x2=3
F(x)=tg²x+3cosx
f(-x)=(-tgx)²+3cos(-x)=tg²x+3cosx (cosx=cos(-x))
f(x)=f(-x)
Ответ четная
<span>AC=h/sin30=30/0.5=60см...... АВ=h/sin75=30/((√2+√6)/4)=30√6-30√2......... BC=√AC²+AB²-2*AC*AB-cos45=√60²+(30√6-30√2)²-2*60*(30√6-30√2)*√2/2=√(14400-7200√3)
</span>
15х + 36х²-(36х²+6х-6х-1)-2,5х=0
<em>cos^2(3x-п/6)=3/4</em>
<em>cos(3x-п/6)=+-sqrt(3)/2</em>
<em>[3x-п/6=п/6+2пn; n e Z;</em>
<em>[3x-п/6=-п/6+2пn; n e Z;</em>
<em> </em>
<em>[3x=п/3+2пn; n e Z;</em>
<em>[3x=2пn; n e Z;</em>
<em>Ответ: </em>
[x=п/9+(2пn)/3; n e Z;
[x=(2пn)/3; n e Z;