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if x^2-2011x+1=0 is true,then waht is the value of x-2010x+2011/(x^2+1)?

 Sep 25, 2014

Best Answer 

 #9
avatar+130477 
+13

x2 = 2011x - 1  →  x2 + 1 = 2011x

So

x^2-2010x+【2011/(x^2+1)] =

[2011x - 1 ] - 2010x + 2011/(2011x) =

x - 1 + 1/x =

[x2 - 1x + 1] / x =

[x2 + 1 - x ] /x =

[2011x - x] / x =

2010x / x =

2010      (with the restriction that x ≠ 0)

 

 Sep 25, 2014
 #1
avatar+118703 
+8

Ifx22011x+1=0$istrue,thenwhatisthevalueof$x2010x+2011(x2+1)?$first$x22011x+1=0x2+1=2011x$now$ x2010x+2011(x2+1)=x2010x+2011(2011x)=x2010x+1x=2009x+1x

 

Maybe you needed more brackets in your question?  I think that you probably did.  

 Sep 25, 2014
 #2
avatar+238 
+8

oh. i am sorry the second equation should be x^2-2010x+2011/(x^2+1)

 Sep 25, 2014
 #3
avatar+118703 
+8

Maybe you really mean this ??

 (x^2-2010x+2011) /(x^2+1)

Is that right?

 Sep 25, 2014
 #4
avatar+238 
+8

x^2-2010x+【2011/(x^2+1)]

 Sep 25, 2014
 #5
avatar+118703 
+8

Ifx22011x+1=0$istrue,thenwhatisthevalueof$x2010x+2011(x2+1)?$first$x22011x+1=0x2+1=2011x$now$ x22010x+2011(x2+1)=x22010x+2011(2011x)=x22010x+1x=(x2+1)12010x+1x=2011x12010x+1x=x1+1x

 

=x2x+1x=1011xxx=1010xx=1010

 

I think I might have stuffed up somewhere.  Plus I have a reputation for doing things the LONG way.

I'm going to look over it some more.   

 Sep 25, 2014
 #6
avatar+118703 
+3

No I think i am happy enough with that answer.   

 Sep 25, 2014
 #7
avatar+8262 
0

Melody. Lol! That was so funny.

 Sep 25, 2014
 #8
avatar+118703 
0

I am glad that you find me entertaining Dragon.  

 Sep 25, 2014
 #9
avatar+130477 
+13
Best Answer

x2 = 2011x - 1  →  x2 + 1 = 2011x

So

x^2-2010x+【2011/(x^2+1)] =

[2011x - 1 ] - 2010x + 2011/(2011x) =

x - 1 + 1/x =

[x2 - 1x + 1] / x =

[x2 + 1 - x ] /x =

[2011x - x] / x =

2010x / x =

2010      (with the restriction that x ≠ 0)

 

CPhill Sep 25, 2014
 #10
avatar+118703 
+8

I thought about the restriction Chris but I didn't put it there because the first statement would not be true if x=0.

 

But like always - yours is shorter.

I started mine from the previous result where the question was wrong.

That is my excuse and I am sticking with it!  LOL  

 Sep 25, 2014
 #11
avatar+130477 
+8

I'll put it down to your "left-handedness".............LOL!!!!!

 

 Sep 25, 2014
 #12
avatar+238 
+8

(x^2-2011x+1)/x=0/x

x-2011+1/x=0

x+1/x=2011

x-1+1/x=2011-1=2010

Good job.Is it funny or not to do problem like this?if yes, i will put a problem everyday to the forum 

 Sep 25, 2014
 #13
avatar+130477 
+8

It IS fun, quinn.......just don't make them too difficult......otherwise, it makes us look bad........

 

P.S  ....I even had to "cheat" off Melody a bit to get that problem correct!!!!  (Shhh!!!...don't tell her)

 

 Sep 25, 2014
 #14
avatar+118703 
+8

Yes I had fun with this problem quinn.

But it is better if you get the question right in the first place.  I liked the Extra brackets that you put in second time round, then we know we have not misinterpreted.

I have included this problem in the next "End of Day Wrap" that i  write.  I invite you to read my wrap.  I write one most nights.

Here is the address of yesterday's one.  They are kept in with the sticky topics.  :)

http://web2.0calc.com/questions/all-questions-answered-to-this-point#r294

(I don't usually include that many questions but I had not written one for a few days)

We really DID LIKE this question Quinn, you are welcome here any time  

 Sep 25, 2014

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