Сosa=20/29
sina=√(1-cos²a)=√(1-400/841)=√(441/841)=21/29
cosb=-8/17
sinb=√1-64/289=√225/289=15/17
sin(a-b)=sinacosb-sinbcosa=21/29*(-8/17)-15/17*20/29=(-168-300)/493=
=-468/493
√ ( 18X^2 - 9 ) = X^2 - 4
( √ 18X^2 - 9 ) = ( X^2 - 4)^2
18X^2 - 9 = X^4 - 8X^2 + 16
X^4 - 8X^2 - 18X^2 + 16 + 9 = 0
X^4 - 26X^2 + 25 = 0
X^2 = A ; A > 0
A^2 - 26A + 25 = 0
D = 676 - 100 = 576 ; √ D = 24
A1 = ( 26 + 24 ) : 2 = 25 ; > 0
A2 = ( 26 - 24 ) : 2 = 1 ; > 0
X^2 = 25
X = 5 ; X = - 5
X^2 = 1
X = 1 ; X = - 1
Ответ 5 ; - 5 ; 1 ; - 1
<em>Ответ: во вложении Объяснение:</em>
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