Löse die folgenden biquadratischen Gleichungen ax4 + bx2 + c = 0

-8.5x4 + 17x2 + 680 = 0
 x1 = 3.16  x2 = -3.16
x3 = ◊  x4 = ◊		4x4 - 44x2 + 96 = 0
 x1 = 2.83  x2 = -2.83
x3 = 1.73  x4 = -1.73
-x4 + 4x2 + 60 = 0
 x1 = 3.16  x2 = -3.16
x3 = ◊  x4 = ◊		-9x4 - 81x2 - 180 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
2.5x4 + 15x2 - 40 = 0
 x1 = 1.41  x2 = -1.41
x3 = ◊  x4 = ◊		-7x4 - 35x2 = 0
 x1 = 0  x2 = 0
x3 = ◊  x4 = ◊
0.5x4 - 3x2 + 4 = 0
 x1 = 1.41  x2 = -1.41
x3 = 2  x4 = -2		-1.5x4 + 1.5x2 + 30 = 0
 x1 = 2.24  x2 = -2.24
x3 = ◊  x4 = ◊
9x4 + 45x2 + 36 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		6x4 + 108x2 + 480 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
-3.5x4 - 17.5x2 + 84 = 0
 x1 = ◊  x2 = ◊
x3 = 1.73  x4 = -1.73		7x4 - 56x2 + 105 = 0
 x1 = 2.24  x2 = -2.24
x3 = 1.73  x4 = -1.73
-4x4 - 24x2 + 64 = 0
 x1 = 1.41  x2 = -1.41
x3 = ◊  x4 = ◊		-7.5x4 + 7.5x2 + 315 = 0
 x1 = ◊  x2 = ◊
x3 = 2.65  x4 = -2.65
5x4 - 85x2 + 350 = 0
 x1 = 2.65  x2 = -2.65
x3 = 3.16  x4 = -3.16		4x4 - 32x2 - 80 = 0
 x1 = 3.16  x2 = -3.16
x3 = ◊  x4 = ◊
1.5x4 - 21x2 + 60 = 0
 x1 = 3.16  x2 = -3.16
x3 = 2  x4 = -2		8.5x4 - 51x2 + 68 = 0
 x1 = 1.41  x2 = -1.41
x3 = 2  x4 = -2
2.5x4 + 5x2 - 7.5 = 0
 x1 = 1  x2 = -1
x3 = ◊  x4 = ◊		2.5x4 - 12.5x2 - 35 = 0
 x1 = ◊  x2 = ◊
x3 = 2.65  x4 = -2.65