help w/ solving by completing the square: x^2 + 4x + 3 = 0

emdorsheimer

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Oct 6, 2006
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These are getting harder because this is a college trying to jam a years worth of schooling into a nine week period.

Solve by completing the square: x^2 + 4x + 3 = 0

Please help with the steps. thanks
 
I'll demonstrate the steps using a different equation:

Quadratic equation:

. . . . .3x<sup>2</sup> + 6x - 5 = 0

Put any constant terms on the other side:

. . . . .3x<sup>2</sup> + 6x = 5

Factor out whatever is multiplied on the square term (if anything):

. . . . .3(x<sup>2</sup> + 2x) = 5

Find half of the coefficient on the linear term:

. . . . .(1/2)(2) = 1

Square, and add to both sides, taking account of the factoring:

. . . . .3(x<sup>2</sup> + 2x + 1) = 5 + 3(1)

Simplify into perfect-square form:

. . . . .3(x + 1)<sup>2</sup> = 8

. . . . .(x + 1)<sup>2</sup> = 8/3

Solve:

. . . . .x + 1 = ± sqrt[8/3]

Simplify as appropriate to obtain the final answer.

Eliz.
 
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