Arthur D. answered 10/24/17
Tutor
4.9
(337)
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
s^2=4s+121
s^2-4s-121=0
(-b±√(b^2-4ac))/2a
(4±√16+484))/2
(4±√500)/2
(4±10√5)/2
2±5√5
2+5√5
check:(2+5√5)^2=4(2+5√5)+121
4+20√5+125=8+20√5+121
129+20√5=129+20√5
the square is 2+5√5 miles or 2+11.18=13.18 miles
13.18 rounded to the nearest tenth is 13.2 miles