Answer:
2nd and 4th equation will have only one solution.
Step-by-step explanation:
1). 4x² + 4x = 0
4x(x + 1) = 0
x = 0
or (x + 1) = 0 ⇒ x = -1
2). x² + 6x + 9 = 0
(x + 3)² = 0
(x + 3) = 0
x = -3
3). 9x² - 25 = 0
9x² = 25
x² = [tex]\frac{25}{9}[/tex]
x = ±[tex]\sqrt{\frac{25}{9} }[/tex]
x = ±[tex]\frac{5}{3}[/tex]
4). 5x² + 20x + 20 = 0
5(x² + 4x + 4) = 0
(x + 2)²= 0
x + 2 = 0
x = -2
5). x² - x - 6 = 0
x² - 3x + 2x - 6 = 0
x(x - 3) + 2(x - 3) = 0
(x + 2)(x - 3) = 0
x = -2 or x = 3
Therefore, 2nd and 4th equations have only one solution.
