Question 558845
The question is WRONG.


as this is a quadratic equequation,we have to consider the value of delta.


Delta=b^2-4ac
=5^2-4(2)(7)
=25-56
=-31<0.

So, there are no real roots for the equation, which is impossible for length.

*[invoke quadratic "x", 2, 5, 7 ]