Which of the following must be non-negative? Options
A) (a-0.9)(a-1)	B) (a+1)(a-1)	C) (a+0.9)(a+1)	D) (a-0.9)(a-0.9)	E) a(a+1)
a^2+a   f'(a)=2a+1=0 =&gt; a=-1/2   f''(a) =2&gt;0 =&gt; a= -1/2 is point of minima Putting this value in main equation we get -1/2 (-ve)   Option D   F(a)=(a - 0.9)^2   f'(a)= 2(a-0.9)=0 =&gt; a=0.9   f''(a)= 2&gt;0 =&gt; a= 0.9 is point of minima. Putting in main equation we get 0 which is non negative.   Answer: (a-0.9)(a-0.9)
<result>D</result>
Which of the following must be non-negative?