Which of the following equation have only one solutions? Select all correct answers.
4x^2+4x=0
X^2+6x+9=0
9x^2-25=0
5x^2+20x+20=0
X^2-x-6=0
4x^2+4x=0
X^2+6x+9=0
9x^2-25=0
5x^2+20x+20=0
X^2-x-6=0