How do you solve $3x^2 – x – 1 = 0$ using the quadratic formula?

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Answer 1 · 2017-08-28T21:00:55

See a solution process below:

For $color(red)(a)x^2 + color(blue)(b)x + color(green)(c) = 0$ , the values of $x$ which are the solutions to the equation are given by:

$x = (-color(blue)(b) +- sqrt(color(blue)(b)^2 - (4color(red)(a)color(green)(c))))/(2 * color(red)(a))$

Substituting:

$color(red)(3)$ for $color(red)(a)$

$color(blue)(-1)$ for $color(blue)(b)$

$color(green)(-1)$ for $color(green)(c)$ gives:

$x = (-color(blue)((-1)) +- sqrt(color(blue)((-1))^2 - (4 * color(red)(3) * color(green)(-1))))/(2 * color(red)(3))$

$x = (1 +- sqrt(color(blue)(1 - (-12))))/6$

$x = (1 +- sqrt(color(blue)(1) + 12))/6$

$x = (1 +- sqrt(13))/6$

How do you solve 3x^2 – x – 1 = 03x^2 – x – 1 = 0 using the quadratic formula?