(-4)^2-4(1)(5)
16-4(1)(5)
16-4(5)
16-20
-4
The discriminant is negative so there are no real number solutions.
First find out how many more inches it needs to grow, 54-37.5; It needs to grow 16.5 more inches. If it grows 3 inches a year then you have to do 16.5/3; 5.5. It will take 5.5 or 5 1/2 more years to grow to 54 inches.
