How do you solve # x^2 - 6x - 3 = 0 #?
1 Answer
Aug 31, 2016
Explanation:
Complete the square then use the difference of squares identity:
#a^2-b^2=(a-b)(a+b)#
with
#0 = x^2-6x-3#
#color(white)(0) = x^2-6x+9-12#
#color(white)(0) = (x-3)^2-(2sqrt(3))^2#
#color(white)(0) = ((x-3)-2sqrt(3))((x-3)+2sqrt(3))#
#color(white)(0) = (x-3-2sqrt(3))(x-3+2sqrt(3))#
Hence:
#x = 3+-2sqrt(3)#