Solve x^2 + 9x + 9 = 0 ((10 points best answer))?

Question

Using the quadratic formula

Answer 1

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a = 1, b = 9, c = 9

- 9 +/- Sqrt(81 - 4*1*9) / 2

- 9 +/- Sqrt(81 - 36) / 2

- 9 +/- Sqrt45 / 2

- 9 +/- Sqrt9*Sqrt5 / 2

- 3 +/- 3Sqrt5 / 2

x = 3/2(-3 - Sqrt5)

x = 3/2(Sqrt5 - 3)

Answer 2

Answer: x = [-9 +/- 3sqrt5]/2

Method:

The quadratic formula states that x = [-b +/- sqrt(b^2 - 4ac)]/2a. In this case, a = 1, b = 9, and c = 9, so just plug those values into the formula:

x = [-9 +/- sqrt(9^2 - 4*1*9)]/2*1

x = [-9 +/- sqrt(81 - 36)]/2

x = [-9 +/- sqrt(45)]/2

x = [-9 +/- 3sqrt5]/2

Answer 3

x^2 + 9*x + 9 = 0

a = 1, b = 9, c = 9

b^2 - 4*a*c = 81 - 4*1*9 = 45 = 9*5

x1 = ( - 9 + 3*sqrt(5))/2 = - 9/2 + (3/2)*sqrt(5)

x2 = - 9/2 - (3/2)*sqrt(5)