Who can help to develop and solve an algebraic equation for this question? ​

Solve the equation 3x2 + 19x + 9 = 0 to the nearest tenth.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

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.