Question

What number must be added to the expression below to complete the square? x2 + 5x

a:25
b:25/4
c:5/2
d:5

Answer 1

You halve the linear coefficient, square that value, and add it.

In this case the linear coefficient is 5 so:

(5/2)^2

25/4

Answer 2

Completing the square would be (b/2)^2, where b here is equal to 5. (5/2)^2 would be 25/4, which would be choice B.