If there is exactly one root of the equation x^2 + ax - b, where a and b are positive constants, what is b in terms of a?
Choose the correct choice from the following
A) a/2	B) a	C) -a^2/4	D) a^2/2	E) a^2/4
one root for a quadratic equation ax^2+bx+c is possible only when b^2 = 4ac ---1   Here b = a   c= b   a = 1   substituting these values in 1, we have   a^2 = -4b =&gt; b =-a^2/4   Answer is -a^2/4.
<result>C</result>
If there is exactly one root of the equation x^2 + ax - b, where a and b are positive constants, what is b in terms of a?