Help. ​

For the first one.....here's a hint......expand each answer.....see if the second one leads you to

y = x^2  + 4x  -  3

For the  second one.....I'll use a graph  [ although I can also solve it algebraically, if you want me to ]

Look at the graph, here.....

https://www.desmos.com/calculator/sic40iw0e7

The height of the arch is ≈ 381 ft   and  the length of the bridge above the arch is ≈ 1791 ft