Find the number that we can place in the box, so that the resulting quadratic is the square of a binomial. \(x^2 + \dfrac{4}{5}x + \boxed{\phantom{000}}\)

:D

I learned this! (x + 4/5)^2 = x^2 + 4/5*x + 16/25, so 16/25 goes in the box.

Sorry guest but that is not correct.

half of 4/5 is 2/5

(2/5)^2 = 4/25

\((x+\frac{2}{5})^2 = x^2+2*\frac{2x}{5}+(\frac{2}{5})^2\)