Problem: The difference of the roots of x2−7x−9=0 is:
Answer Choices:
A. +7
B. +27​
C. +9
D. 285​
E. 85​
Solution:
The roots are (7±49+36​)/2 and their difference is 27+85​​−27−85​​=85​ or 27−85​​−27+85​​=−85​.
Of the given choices, (E) is correct.