Answer :

caylus
Hello,

x=0==> y=0
y=0==> x²+3x=0==>x(x+3)=0==>x=0 or x=-3

x²+y²+3x=0
==>(x²+2*3/2x+9/4)+y²=9/4
==>(x+3/2)²+y²=(3/2)²
is the equation of the circle of center (-3/2,0) and radius 3/2 where the tangent to the circle at (0,0) is the axis 0y.

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