y=(x^2)/(10)-3x

Solution for y=(x^2)/(10)-3x equation:

x in (-oo:+oo)

y = (x^2)/10-(3*x) // - (x^2)/10-(3*x)

3*x-((x^2)/10)+y = 0

3*x-1/10*x^2+y = 0

DELTA = 3^2-(-1/10*4*y)

DELTA = 2/5*y+9

2/5*y+9 = 0

2/5*y+9 = 0 // - 9

2/5*y = -9 // : 2/5

y = -9/2/5

y = -45/2

DELTA = 0  <=>  t_1 = -45/2

x = -3/(-1/10*2) i y = -45/2

x = 15 i y = -45/2

( x = ((2/5*y+9)^(1/2)-3)/(-1/10*2) or x = (-(2/5*y+9)^(1/2)-3)/(-1/10*2) ) i y > -45/2

( x = -5*((2/5*y+9)^(1/2)-3) or x = 5*((2/5*y+9)^(1/2)+3) ) i y > -45/2

y+45/2 > 0

y+45/2 > 0 // - 45/2

y > -45/2

x in { 15, -5*((2/5*y+9)^(1/2)-3), 5*((2/5*y+9)^(1/2)+3) }