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Solve by completing the square: x2+4x-5=0

1 Answer

2 votes

Answer:

The solutions are {-5, 1}

Explanation:

Next time, please use the symbol " ^ " to denote exponentiation:

x^2+4x-5=0

Start by identifying the coefficient of the x term (it is 4 here). Divide this by 2, resulting in 2. Square this result (square 2), obtaining 4.

Now add this 4 after the 4x term, and then subtract this 4:

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

Rewrite x^2+4x + 4 as (x + 2)²:

(x + 2)² - 9 = 0

Add 9 to both sides, to isolate (x + 2):

(x + 2)² = 9

Take the square root of both sides:

x + 2 = ±3

Solve for x: x = -2 + 3, or 1

x = -2 - 3, or -5

The solutions are {-5, 1}

User Dustin Hodges
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