# How do you solve using the completing the square method #a²-a-1=0#?

##### 1 Answer

Mar 21, 2016

#### Answer:

#### Explanation:

First multiply the whole equation by

#0 = 4a^2-4a-4#

#= 4a^2-4a+1-5#

#= (2a-1)^2-(sqrt(5))^2#

#= ((2a-1)-sqrt(5))((2a-1)+sqrt(5))#

#= (2a-1-sqrt(5))(2a-1+sqrt(5))#

Hence:

#a=(1+-sqrt(5))/2#