Question 347798
area = 5 sq.m
perimeter = 24
..
l*b= 5
l= 5/b
2(l+b)=24
l+b=12
plug value of l 
5/b +b=12
5+b^2/ b =12
(5+b^2)  =12b
b^2-12b+5 =0
solve the equation using quadratic formula
you will get 
length =11.57
width = 0.43
CHECK 
11.57*0.43= 4.98
find diagonal