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

9x4 + 81x2 + 72 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		2x4 + 4x2 - 160 = 0
 x1 = 2.83  x2 = -2.83
x3 = ◊  x4 = ◊
9.5x4 - 85.5 = 0
 x1 = 1.73  x2 = -1.73
x3 = ◊  x4 = ◊		1.5x4 - 15x2 + 37.5 = 0
 x1 = 2.24  x2 = -2.24
x3 = 2.24  x4 = -2.24
-6.5x4 - 32.5x2 = 0
 x1 = ◊  x2 = ◊
x3 = 0  x4 = 0		-5.5x4 - 71.5x2 - 220 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
5.5x4 + 33x2 - 88 = 0
 x1 = 1.41  x2 = -1.41
x3 = ◊  x4 = ◊		-0.5x4 + 4x2 - 3.5 = 0
 x1 = 2.65  x2 = -2.65
x3 = 1  x4 = -1
5x4 + 5x2 - 210 = 0
 x1 = 2.45  x2 = -2.45
x3 = ◊  x4 = ◊		6x4 + 18x2 - 240 = 0
 x1 = ◊  x2 = ◊
x3 = 2.24  x4 = -2.24
4x4 - 20x2 = 0
 x1 = 0  x2 = 0
x3 = 2.24  x4 = -2.24		6.5x4 - 45.5x2 = 0
 x1 = 0  x2 = 0
x3 = 2.65  x4 = -2.65
-x4 - 16x2 - 60 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		-5x4 - 55x2 - 90 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊
-3.5x4 + 7x2 + 168 = 0
 x1 = ◊  x2 = ◊
x3 = 2.83  x4 = -2.83		7.5x4 + 67.5x2 = 0
 x1 = ◊  x2 = ◊
x3 = 0  x4 = 0
4x4 + 28x2 = 0
 x1 = ◊  x2 = ◊
x3 = 0  x4 = 0		2.5x4 + 2.5x2 - 105 = 0
 x1 = 2.45  x2 = -2.45
x3 = ◊  x4 = ◊
8.5x4 + 42.5x2 + 34 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊		-10x4 - 70x2 - 60 = 0
 x1 = ◊  x2 = ◊
x3 = ◊  x4 = ◊