Homework Help: Math

Posted by Maria on Tuesday, March 31, 2009 at 7:01pm.

x-sqrt(2x+1) = 7

My answer:
same as:

x - 7 = sqrt(2x+1)
==>

x^2 - 14x + 49 = 2x+1 ==>

x^2 - 16x + 48 = 0

split this up into:

(x - 12) * ( x - 4 ) = 0

so, x can technically be 12 or 4

12 - sqrt(24+1) does = 7

x=12

Math - betty, Tuesday, March 31, 2009 at 7:09pm
wrong...
x^2 times (2x+1 )
equals 2x^3 + 2x^2 -7 =0
Math - betty, Tuesday, March 31, 2009 at 7:12pm
ohhh I'm so sorry. I misread the question...but your answer is still wrong
you would square both sides by 2
and then and up w/ 2x+1 = 49
Math - Maria, Tuesday, March 31, 2009 at 7:15pm
What about the x?
Math - Reiny, Tuesday, March 31, 2009 at 7:49pm
Maria, you are correct

x = 12 is the right answer, since x= 4 does not verify when you try it back in the original.

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