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

Question

62740 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-05-31T00:08:35

Using the quadratic formula, #x# can either # =-2.618 or -0.382#

#a x^2 + bx + c = 0#

#1 x^2 + 3x + -1 = 0#

#a = 1#
#b = 3#
#c = -1#

#x = (-b +- sqrt(b^2-4ac))/(2a)#

#x = (-3 +- sqrt(3^2-4 xx 1 xx -1))/(2 xx 1)#

#x = (-3 +- sqrt(9- 4))/2#

#x = (-3 +- sqrt5)/2#

#x = (-3 +- 2.236)/2#

#x_1 = (-3 - 2.236)/2#

#x_1 = (-5.236)/2#

#color(blue)(x_1 = -2.618#

#x_2 = (-3 + 2.236)/2#

#x_2 = (-0.764)/2#

#color(blue)(x_2 = -0.382#