Answer is
a) x^2 + 10x + 25
b) x^2 + 16x + 64
c) x^2 + 6x + 9
These are shown in the attachment.
For each set, you label the first expression on top and the second equation on the side. Multiply the matching numbers to the open box. Combine like terms. Make sure you write them in standard form (largest to smallest exponents) which the box method pretty much does for you. You can use these boxes with any set of polynomials.