Question 489149
4n2+(4(n+7))2=(52)2
4n2+(4n+28)2=2704
4n2+16n2+224n+784=2704
20n2+224n-1920=0
5n2+56n-480=0
*[invoke quadratic "x", 5, 56, -480 ]
Throwing out the negative answer, we get the speed of the southbound boat to be 5.68538878373271 mph..