X4 + 6x² - 4 = 0
замена y = x²
y² + 6y - 4 = 0
D = b2 - 4ac = 62 - 4·1·(-4) = 36 + 16 = 52
y1 = -6 - √52
------------- ≈ -6.6056
2·1
y2 = -6 + √52
------------- ≈ 0.60555
2·1
x² = -6 - √52
------------
2
x² = -6 + √52
-------------
2
x1 = (-6 + √52)1/2 ≈ 0.77817
---------------
2
x2 = -(-6 + √52)1/2 ≈ -0.77817
--------------------
2