Review: Solve xsquare - 4x = -1 for X

wallee

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Apr 20, 2008
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Ok so now I am really confused. This is a review problem for algebra: xsquare -4x+1=0. I need to solve for x. I dont think I factor because this problem is prime, maybe complete the square:

xsquare-4x=-1
xsquare-4x+4=3
then i get confused..
 
Re: Review: Solve for X

x[sup:s7n53ozh]2[/sup:s7n53ozh]-4x=-1
x[sup:s7n53ozh]2[/sup:s7n53ozh]-4x+4=3
then i get confused..


Now factor the left side and write as a binomial squared. Then you are in position to take the square root of both sides and go from there. When you take the square root of both sides don't forget that the right side will be preceded by a "plus or minus" sign.
 
Re: Review: Solve for X

so i get x-2 under the radical=3 under the radical. is this my final answer?
 
Re: Review: Solve for X

Nope. If you take the square root of say (a+b)[sup:1lqm6nms]2[/sup:1lqm6nms] you get \(\displaystyle \pm\)(a+b).
 
Re: Review: Solve for X

xsquare-4x=-1
xsquare-4x+4=3

Loren has described what you need to do. Read his explanation carefully.

x^2 – 4x = -1
x^2 – 4x + 4 = 3
(x-2)^2 = 3
[(x-2)^2]^(1/2) = +/- [3^(1/2)]
(x-2) = +/- [3^(1/2)]

x = 2 +/- [3^(1/2)]

[Note: “^” indicates an exponent, and an exponent of (1/2) is the same as the “square root/radical.”]

x equals two plus or minus the square root of three.

Hope that helps.
 
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