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SOLUTION: Solve by completing the square: x^2+4x-5=0
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Question 178395
This question is from textbook
:
Solve by completing the square: x^2+4x-5=0
This question is from textbook
Answer by
jim_thompson5910(33401)
(
Show Source
):
You can
put this solution on YOUR website!
Start with the given expression.
Take half of the
coefficient
to get
. In other words,
.
Now square
to get
. In other words,
Now add
and
subtract
. Make sure to place this after the "x" term. Notice how
. So the expression is not changed.
Group the first three terms.
Factor
to get
.
Combine like terms.
So after completing the square,
transforms to
. So
.
So
is equivalent to
.
---------------------------------------------------------
Now let's solve
Start with the given equation.
Add
to both sides.
Combine like terms.
Take the square root of both sides.
or
Break up the "plus/minus" to form two equations.
or
Take the square root of
to get
.
or
Subtract
from both sides.
or
Combine like terms.
--------------------------------------
Answer:
So the solutions are
or
.