Some one please help me with this question

What is the square root of 45? (step by step working plz)

Which of the following lines does not intersect the line y=-2x+3 ? a) y=2x b) y=2x-3 c) y=2x+3 d) y=-2x-3

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).