8,3-4 7/15=83/10-67/15=(124,5-67)/15=575/150=23/6=3 5/6.
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<span>a)y=2sinx+cosx если х=-п/2; x=п/6
y=2sin-</span>π/2+cos -π/2=-2+0=-2
y=2sinπ/6+cosπ/6=1+√3/2
<span>
б)y=cos x-x</span>²<span>если x=-п/3; x=-п
</span> y=cosπ/3-π²/9=1/2-π²/9
y=cos-π-π²=-1-π²
<span>в)y=2cos(x-п/4)-1,если x=-п/2;x=п/4
</span> y=2cos(-π/2-π/4)-1=2cos(3π/4)-1=-√2/2-1
y=2cos0-1=2-1=1
2х(2)-18=0/:2
х(2)-9=0
(х+9)(х-9)=0
х=9,х=-9