What number must be added to make a perfect square trinomial

x^2+(8/5)x

16/25

(8/5)/2=.8
.8^2=(16/25)

To make the expression x^2 + (8/5)x a perfect square trinomial, we need to add a constant term in such a way that it can be factored into the square of a binomial.

Let's break down the steps to find the number we need to add:

1. Take half of the coefficient of the x term: (8/5) / 2 = 4/5.
2. Square the result: (4/5)^2 = 16/25.

The number we need to add to make the expression a perfect square trinomial is 16/25.

So, the complete perfect square trinomial is:

x^2 + (8/5)x + 16/25