Question

To complete the square, how do you find the value that must be added to the expression to make a perfect square trinomial? What is the value?
x^2 + 2/5x + ?
A) square 2/5 and add to both sides; 4/25
B) take half of 2/5 and add to both sides; 1/5
C) square half of 2/5 and add to both sides; 1/25
D) take half of 2/5 and add the opposite to both sides; −1/5

Answer 1

Take half of the coefficient of x (which is 2/5) and square it:

[ (1/2)(2/5) ]^2 = (1/5)^2 = 1/25, or 0.04

Thus, to rewrite x^2 + (2/5)x to include a perfect square trinomial,

x^2 + (2/5)x  = x^2 + (2/5)x + (1/5)^2 - (1/5)^2, or

                 (x+1/5)^2 - (1/5)^2, or (x + 1/5)^2 - 1/25

Answer 2

Answer:The answer is C

Step-by-step explanation: