c=10000+3x+x2/8000

Solution for c=10000+3x+x2/8000 equation:

x in (-oo:+oo)

c = (x^2)/8000+3*x+10000 // - (x^2)/8000+3*x+10000

c-((x^2)/8000)-(3*x)-10000 = 0

c-((x^2)/8000)-3*x-10000 = 0

c-1/8000*x^2-3*x-10000 = 0

DELTA = (-3)^2-(-1/8000*4*(c-10000))

DELTA = 1/2000*(c-10000)+9

1/2000*(c-10000)+9 = 0

1/2000*(c-10000)+9 = 0

1/2000*c+4 = 0

1/2000*c+4 = 0

1/2000*c+4 = 0 // - 4

1/2000*c = -4 // : 1/2000

c = -4/1/2000

c = -8000

DELTA = 0  <=>  t_1 = -8000

x = 3/(-1/8000*2) i c = -8000

x = -12000 i c = -8000

( x = ((1/2000*(c-10000)+9)^(1/2)+3)/(-1/8000*2) or x = (3-(1/2000*(c-10000)+9)^(1/2))/(-1/8000*2) ) i c > -8000

( x = -4000*((1/2000*(c-10000)+9)^(1/2)+3) or x = -4000*(3-(1/2000*(c-10000)+9)^(1/2)) ) i c > -8000

c+8000 > 0

c+8000 > 0 // - 8000

c > -8000

x in { -12000, -4000*((1/2000*(c-10000)+9)^(1/2)+3), -4000*(3-(1/2000*(c-10000)+9)^(1/2)) }