Solve the equation?

0 ⤊

-2x^2-16x-21=0

#28

2007-07-31 06:17:06 · 3 answers · asked by Kristin R 2 in Science & Mathematics ➔ Mathematics

3 answers

2x² + 16x + 21 = 0
x = [ -16 ± √(256 - 168) ] / 4
x = [- 16 ± √88 ] / 4
x = [- 16 ± 2√22 ] / 4
x = (1/2) [- 8 ± √22 ]

2007-07-31 06:43:08 · answer #1 · answered by Como 7 · 0⤊ 0⤋

Multiply both the sides by -1 :
2x^2 + 16x + 21 = 0

Use the quadratic formula to solve :
x = [ -16 +/- sqrt.(256 - 168) ] / 4
= [ -16 +/- 2*sqrt. 22 ] / 4

So x = ( sqrt.22 - 8 ) / 2 , ( -sqrt.22 - 8 ) / 2

Hope this helps.

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2007-07-31 13:32:27 · answer #2 · answered by Prashant 6 · 0⤊ 0⤋

Use quadratic formula:
[16 +/- sqrt(256 - 168)]/-4 = -4 +/- sqrt(22)/-2 = -4 + 2.345 or
-4 - 2.345 = -1.655, -6.345

2007-07-31 13:35:29 · answer #3 · answered by John V 6 · 0⤊ 0⤋