Question 33426
1st: Divide the 20 by 2 and square the result to get 100
x^2+20x+100 is a perfect square.

2nd: Divide the (-3/4) by 2 to get (-3/8) then square to get 9/64
x^2-(3/4)x+(9/64) is a perfect square.
Cheers,
Stan H.