4x^2 + 4x - 11=8? | fedest.com

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4x^2 + 4x - 11=8?

Solve by completing the square

2007-05-28 15:49:46 · 3 answers · asked by Anonymous in Education & Reference ➔ Homework Help

3 answers

4x^2 + 4x - 11 = 8
4x^2 + 4x - 19 = 0
[4x^2 + 2(2x)(1) + (1)^2] - (1)^2 - 19 = 0
(4x + 1)^2 - 1 - 19 = 0
(4x + 1)^2 - 20 = 0
(4x + 1)^2 = 20
4x + 1 = +/- 2 * sqrt 5
4x = -1 +/- (2*sqrt 5)
x = [-1 +/- (2 * sqrt 5)]/4

2007-05-28 15:55:57 · answer #1 · answered by Akilesh - Internet Undertaker 7 · 1⤊ 0⤋

x can equal either:

-2.73607 or 1.73607

2007-05-28 16:01:30 · answer #2 · answered by kcdude 5 · 0⤊ 1⤋

subtract 8 from both sides, then do the quadratic equation:

i forgot it, but thats wat u have to do

2007-05-28 15:55:04 · answer #3 · answered by tjtigers13 2 · 0⤊ 2⤋