Match each expression with the value needed on the under-score in order for the expression to be a perfect square trinomial.
A. x^2-8x+__
B. x^2+20x+__
C. x^2-16x+__
D.x^2+9x+__
1. 16
2. 20.25
3. 64
4. 100
A. x^2-8x+16 (C)
B. x^2+20x+100 (4)
C. x^2-16x+64 (3)
D. x^2+9x+20.25 (B)