Question

Use the quadratic formula to solve for x. 3x2 + 2x - 6 = 0

Answer 1

Answer:

x = 1/3 (sqrt(19) - 1) or x = (1/3 (-1 - sqrt(19)))

Step-by-step explanation:

Solve for x over the real numbers:

3 x^2 + 2 x - 6 = 0

Using the quadratic formula, solve for x.

x = (-2 ± sqrt(2^2 - 4×3 (-6)))/(2×3) = (-2 ± sqrt(4 + 72))/6 = (-2 ± sqrt(76))/6:

x = (-2 + sqrt(76))/6 or x = (-2 - sqrt(76))/6

Simplify radicals.

sqrt(76) = sqrt(4×19) = sqrt(2^2×19) = 2sqrt(19):

x = (2 sqrt(19) - 2)/6 or x = (-2 sqrt(19) - 2)/6

Factor the greatest common divisor (gcd) of -2, 2 sqrt(19) and 6 from -2 + 2 sqrt(19).

Factor 2 from -2 + 2 sqrt(19) giving 2 (sqrt(19) - 1):

x = 1/6(2 (sqrt(19) - 1)) or x = (-2 sqrt(19) - 2)/6

In (2 (sqrt(19) - 1))/6, divide 6 in the denominator by 2 in the numerator.

(2 (sqrt(19) - 1))/6 = (2 (sqrt(19) - 1))/(2×3) = (sqrt(19) - 1)/3:

x = (1/3 (sqrt(19) - 1)) or x = (-2 sqrt(19) - 2)/6

Factor the greatest common divisor (gcd) of -2, -2 sqrt(19) and 6 from -2 - 2 sqrt(19).

Factor 2 from -2 - 2 sqrt(19) giving 2 (-sqrt(19) - 1):

x = 1/3 (sqrt(19) - 1) or x = 1/6(2 (-1 - sqrt(19)))

In (2 (-sqrt(19) - 1))/6, divide 6 in the denominator by 2 in the numerator.

(2 (-sqrt(19) - 1))/6 = (2 (-sqrt(19) - 1))/(2×3) = (-sqrt(19) - 1)/3:

Answer:  x = 1/3 (sqrt(19) - 1) or x = (1/3 (-1 - sqrt(19)))