How do you solve #x^2 -4x -5=0#?

1 Answer
Don't Memorise
Jun 28, 2015

The solutions are
#color(blue)(x=5, x=-1#

Explanation:

# x^2-4x-5=0#

We can first factorise this expression by splitting the middle term and then find the solutions:

# x^2 color(blue)(-5x +1x)-5=0#

# x( x - 5) + 1 (x-5)=0#
#=color(blue)((x-5)(x+1)#

Equating the factors with zero to obtain the solutions:

  • #x-5 = 0 , color(blue) (x=5#
  • #x+1 = 0, color(blue)(x=-1#
Related questions
See all questions in Completing the Square
Impact of this question
2931 views around the world
You can reuse this answer
Creative Commons License