If both m and n are negative integers, which of the following must be positive?
Select
A) m/n-1  B) m(n+1)  C) mn-5  D) m^2+n^2-1  E) mn+3n
Given m and n are negative integers.   Now take m = -1 and n = -1. sub these values in options..   A) m/n-1 = -1/-1 - 1= 
<gadget id="calculator">-1/-1 - 1</gadget>
<output>0</output>
0.   B. m(n+1)= 0   C. mn-5 = -4   D. m^2+n^2-1 = 1   E. mn+3n = -4   If we take any negative value , say m = -1 or n = -2 etc..only D satisfies...   ANSWER:m^2+n^2-1
<result>D</result>
If both m and n are negative integers, which of the following must be positive?