Select the approximate values of x that are solutions to f(x) = 0, where f(x) = -3x2 + 3x + 9.

Question

Select the approximate values of x that are solutions to f(x) = 0, where
f(x) = -3x2 + 3x + 9.

Answer 1

0 = -3x² + 3x + 9

 

Use the quadratic formula:

 

x = (-b/2a) ± (1/2a)√(b²-4ac)

 

Where a is the coefficient of the x² term, b is the coefficient of the x term and c is the constant term,  In your case, a=-3, b=3,c=9:

 

x = (3/6) ± (1/6)√(3²-4(-3)(9))

x = 1/2 ± (1/2)√117

x = 1/2 ± (1/6)√9*13

 

x = 1/2 ± (1/2)√13

 

Use your calculator to compute the approximate value of the √13 to get the two answers.