X^4 - 7X^2 + 12 = 0
----------------------
X^2 = A ( A > 0 )
A^2 - 7A + 12 = 0
D = 49 - 48 = 1 ; √ D = 1
A1 = ( 7 + 1 ) : 2 = 4
A2 = 6 : 2 = 3
----------------
X^2 = A
-----------
X^2 = 4
X1 = 2
X2 = ( - 2 )
----------
X^2 = 3
X3 = √ 3
X4 = - √ 3
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Уравнение 2
X^4 - 11X^2 + 18 = 0
---------
X^2 = A ( A > 0 )
A^2 - 11A + 18 = 0
D = 121 - 72 = 49 ; √ D = 7
A1 = ( 11 + 7) : 2 = 9
A2 = 4 : 2 = 2
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X1 = 3
X2 = - 3
X3 = √ 2
X4 = - √ 2