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March 2, 2015

March 2, 2015

Posted by **Jon** on Wednesday, February 20, 2008 at 11:22am.

A)-4+-(sqrt10)

B)-4+-(sqrt22)/6

C)-2+-2(sqrt10)/3

D)-4+-(sqrt10)/6

I chose C

x=-b+-(sqrtb^2-4ac)/2a

x=--8+-(sqrt-8^2-4(6)(1))/2(6)

x=8+-(sqrt64-24)/12

x=8+-(sqrt40)/12

x= C

- Math -
**Reiny**, Wednesday, February 20, 2008 at 11:32amcorrect

- Math -
**drwls**, Wednesday, February 20, 2008 at 11:40amIn the first one a = 6, b = 8 and c = 1

x = [-8 +-sqrt (64-24)]/12

=[-8 +-sqrt(4*10)]/12

=[-8 +-2sqrt(10)]/12

=[-4 +-sqrt10]/6

So your amswer is wrong.

- Math -
**Reiny**, Wednesday, February 20, 2008 at 12:06pmThanks for picking up on that

As George would have said,

"I guess I mislooked"

- Math -
- Math(im confused) -
**Jon**, Wednesday, February 20, 2008 at 12:50pmPlease explain x = [-8 +-sqrt (64-24)]/12

=[-8 +-sqrt(4*10)]/12

- Math -
**drwls**, Wednesday, February 20, 2008 at 1:03pm64 - 24 = 40 = 4*10

- Math(so how is my answer wrong? -
**Jon**, Wednesday, February 20, 2008 at 1:10pmi dont understand

- Math -
**drwls**, Wednesday, February 20, 2008 at 1:52pmWhich don't you understand:

64-24 = 40, or

40 = 4 x 10?

Or my use of * for x when multiplying?

We do that often here to avoid confusion with the algebraic variable x.

- Math(so how is my answer wrong? -
- Math(please explain b/c I don't think im wrong) -
**Jon**, Wednesday, February 20, 2008 at 1:07pmI did all the steps

- Math -
**Damon**, Wednesday, February 20, 2008 at 1:28pma = 6

b = 8

c = 1

why did you use -8 for b?

why dis you not divide -b by 2a?

you left a bracket out, wrecking everything

x = [ -8 +/- sqrt (64 - 4*6*1) ] /2*6

x = [ -8 +/- sqrt(64-24) ] / 12

x = [ -8 +/- sqrt (4*10) ] /12

x = [ -8 +/- 2 sqrt (10) ] / 12

x = [ -4 +/- sqrt(10) ] / 6

I agree with drwls :)

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