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

I've seen similar problems, but I don't know how to solve them! Help please!

SavvyBee Apr 13, 2020

#1**+1 **

I think your question is

x^{2} + 4/5 x + ? We need to 'complete the square' take 1/2 of the x coefficient (2/5) , square it , and add it to the equation

(x^{2} + 4/5 x + 4/25) then it becomes

(x+2/5)^2

ElectricPavlov Apr 13, 2020