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

9x4 - 72x2 - 180 = 0
 x1 = 3.16  x2 = -3.16
x3 = ◊  x4 = ◊		6.5x4 + 39x2 + 58.5 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
9.5x4 - 47.5x2 - 475 = 0
 x1 = 3.16  x2 = -3.16
x3 = ◊  x4 = ◊		-3x4 + 24x2 = 0
 x1 = 2.83  x2 = -2.83
x3 = 0  x4 = 0
-9x4 + 9x2 + 810 = 0
 x1 = ◊  x2 = ◊
x3 = 3.16  x4 = -3.16		4x4 + 44x2 + 120 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
0.5x4 - x2 - 7.5 = 0
 x1 = 2.24  x2 = -2.24
x3 = ◊  x4 = ◊		9x4 + 90x2 + 81 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
2x4 + 18x2 = 0
 x1 = ◊  x2 = ◊
x3 = 0  x4 = 0		-8.5x4 + 8.5x2 + 255 = 0
 x1 = ◊  x2 = ◊
x3 = 2.45  x4 = -2.45
2x4 + 22x2 + 56 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		8x4 + 48x2 = 0
 x1 = 0  x2 = 0
x3 = ◊  x4 = ◊
-0.5x4 + 4x2 - 3.5 = 0
 x1 = 2.65  x2 = -2.65
x3 = 1  x4 = -1		4.5x4 - 13.5x2 + 9 = 0
 x1 = 1  x2 = -1
x3 = 1.41  x4 = -1.41
-3x4 - 18x2 - 15 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		9x4 + 36x2 = 0
 x1 = ◊  x2 = ◊
x3 = 0  x4 = 0
-3x4 + 12x2 = 0
 x1 = 0  x2 = 0
x3 = 2  x4 = -2		4.5x4 - 4.5x2 - 324 = 0
 x1 = ◊  x2 = ◊
x3 = 3  x4 = -3
1.5x4 + 27x2 + 120 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		7x4 - 112x2 + 420 = 0
 x1 = 2.45  x2 = -2.45
x3 = 3.16  x4 = -3.16