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(-3/30)*x^3+3*x^2 = 400 // - 400
(-3/30)*x^3+3*x^2-400 = 0
(-1/10)*x^3+3*x^2-400 = 0
(-1/10)*x^3+3*x^2-400 = 0 // * 0
{ 1, -1, 2, -2, 4, -4, 5, -5, 8, -8, 10, -10, 16, -16, 20, -20, 25, -25, 32, -32, 40, -40, 50, -50, 80, -80, 100, -100, 125, -125, 160, -160, 200, -200, 250, -250, 400, -400, 500, -500, 800, -800, 1000, -1000, 2000, -2000, 4000, -4000 }
1
x = 1
30*x^2-x^3-4000 = -3971
1
-1
x = -1
30*x^2-x^3-4000 = -3969
-1
2
x = 2
30*x^2-x^3-4000 = -3888
2
-2
x = -2
30*x^2-x^3-4000 = -3872
-2
4
x = 4
30*x^2-x^3-4000 = -3584
4
-4
x = -4
30*x^2-x^3-4000 = -3456
-4
5
x = 5
30*x^2-x^3-4000 = -3375
5
-5
x = -5
30*x^2-x^3-4000 = -3125
-5
8
x = 8
30*x^2-x^3-4000 = -2592
8
-8
x = -8
30*x^2-x^3-4000 = -1568
-8
10
x = 10
30*x^2-x^3-4000 = -2000
10
-10
x = -10
30*x^2-x^3-4000 = 0
-10
x+10
40*x-x^2-400
30*x^2-x^3-4000
x+10
x^3+10*x^2
40*x^2-4000
-40*x^2-400*x
-400*x-4000
400*x+4000
0
40*x-x^2-400 = 0
DELTA = 40^2-(-400*(-1)*4)
DELTA = 0
x = -40/(-1*2)
x = 20 or x = 20
x in { 20, 20, -10}
x in { 20, 20, -10 }
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