I passed my exam lets go

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

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Awater holding tank measures 105 m long, 50 m wide, and 8 m deep. traces of mercury have been found in the tank, with a concen- tration of 60 mg/l. what is the total mass of mercury in the tank? answer in units of kg.