A train of length 180 m approaches a tunnel of length 620 m. How long will it take the train to pass completely through the
tunnel at a speed of 54 km/h?

After coming out of the tunnel it has to travel it's own length to pass through the tunnel completely. So the train of length 180 metres takes 0.889 seconds to pass through a tunnel of length 680 metres completely.

Answer to your question: a. the fundamental theorem of algebra tells you that the equation will have two complex roots since the degree of the polynomial is 2. the roots are ​ x=1±i7√2 .number of roots=degree of polynomialhere, degree of polynomial is 2 so number of roots will be 2.hope it *_*