Help!! Please

Help!! Please

Short Answer:

To complete the square with the following algebraic expression, what should the third term of the trinomial be?

x²+5/3x+_?

I asume: $x^2+\frac{5}{3}x +\ ? =$

$\begin{array}{|rcll|} \hline (x+a)^2 &=& x^2+\underbrace{2a}_{=\frac53}x+a^2 \\ && 2a = \frac53 \\ && a = \frac{5}{6} \\ && a^2 = \frac{5^2}{6^2} \\ && = \frac{25}{36} \\ \hline \end{array}$

The third term of the trinomial is $\mathbf{\frac{25}{36}}$

short answer:  (1/2b)^2