X^3 + 5X^2 - 4X - 20 = ( X^3 + 5X^2) - ( 4X + 20 ) = X^2 *( X + 5) - 4 * ( X + 5 ) =
= ( X + 5)*( X^2 - 4) = ( X + 5)*( X + 2)*( X - 2 )
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X^2 + 3X - 10 = ( X - 2)*( X + 5 )
D = 9 -4*1*(-10) = 49
V D = 7
X1 = ( - 3 + 7 ) : 2 = 2
X2 = ( - 10 ) : 2 = ( - 5 )
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Сокращаем числитель и знаменатель на ( Х -2)* ( X + 5), получаем
ОТВЕТ: ( Х + 2 )
4,526+12(1/5)-(4(2/3)*1,8-4,526)=4,526+12,2-((14/3)*(9/5)+4,526=
=16,726-(8,4+4,526)=16,726-12,926=3,8.
2sinxcosx+√3cosx=0
cosx(2sinx+√3)=0
cosx=0⇒x=π/2+πn
sinx=-√3/2⇒x=(-1)^n+1 *π/3+πn