How do you solve (sqrt2)x² - x - 3(sqrt2) =0?

1 Answer
Stefan V.
Aug 31, 2015

x_(1,2) = (1 +- 5)/(2sqrt(2))

Explanation:

You know that for a general form quadratic equation

color(blue)(ax^2 + bx + c = 0)

you can find its roots by using the quadratic formula

color(blue)(x_(1,2) = (-b +- sqrt(b^2 - 4ac))/(2a))

In your case, a = sqrt(2), b = -1, and c = -3sqrt(2). This means that you have

x_(1,2) = ((-1) +- sqrt((-1)^2 - 4 * sqrt(2) * (-3sqrt(2))))/(2 * sqrt(2))

x_(1,2) = (1 +- sqrt(1 + 12 * 2))/(2sqrt(2))

x_(1,2) = (1 +- 5)/(2sqrt(2))

The two solutions to this equation will be

x_1 = (1 + 5)/(2sqrt(2)) = color(green)((3sqrt(2))/2)" " and " "x_2 = (1 - 5)/(2sqrt(2)) = color(green)(-sqrt(2))

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