SOLUTION: Using the quadratic equation x2 - 4x - 5 = 0, perform the following tasks: a) Solve by factoring. Answer: Show work in this space. b) Solve by completing the square.

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Question 52431This question is from textbook College Algebra
: Using the quadratic equation x2 - 4x - 5 = 0, perform the following tasks:
a) Solve by factoring.
Answer:
Show work in this space.

b) Solve by completing the square.
Answer:
Show work in this space.

c) Solve by using the quadratic formula.
Answer:
Show work in this space

This question is from textbook College Algebra

Answer by funmath(2933) (Show Source):
You can put this solution on YOUR website!
x^2-4x-5=0
Factoring: Two numbers that multiply together to give you -5 but add together to give you -4 are -5 and +1.
(x-5)(x+1)=0
x-5=0
x-5+5=0+5
x=5
x+1=0
x+1-1=0-1
x=-1
x=-1 and x=5
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Complteting the square:
x^2-4x-5=0
x^2-4x-5+5=0+5
x^2-4x=5
x^2-4x+(-4/2)^2=5+(-4/2)^2
x^2-4x+(-2)^2=5+(-2)^2
x^2-4x+4=5+4
(x-2)^2=9
sqrt((x-2)^2)=(+or-)sqrt(9)
x-2=(+or-)3
x-2+2=+2(+or-)3
x=2(+or-)3
x=2-3=-1
x=2+3=5
x=-1 and x=5
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x^2-4x-5=0
a=1;b=-4;c=-5

x=(-(-4)+or-sqrt((-4)^2-4*(1)*(-5))/(2*1)
x=(4+or-sqrt(16+20))/2
x=(4+or-sqrt(36))/2
x=(4+or-6)/2
x=(4-6)/2
x=(-2)/2
x=-1
x=(4+6)/2
x=10/2
x=5
x=-1 and x=5