taking common factors
y (y'-y-20)=0
there are two possible solutions
y=0
or
y'-y-20y=0
thus using the formula
[tex] ( - b + or - \sqrt{ {b}^{2} - 4ac} ) \div 2a[/tex]
where a is 1 b is -1 and c is -20
but as you substitute the answer inside the root is negative and that cant be possible so the question has no zero and the only possible solution is
y=0
