Find the axis of symmetry. Question in pic. PLEASE HELP

An equation of the line tangent to y=x^3+3x^2+2 at its point of inflection is

What’s the range cuz i can’t find it?

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.