Simplify. The result should involve exactly 1 ratio.
(1/x - x/ x+1) / (2/x+1 - x-1/x)
\[\frac{ \frac{ a }{ b } }{ \frac{ c }{ d } }=\frac{ a }{ b }\times \frac{ d }{ c }\]
can you please help?
simplify it? because I am confused...
Combine the fractions in the top of the ratio first... \[\frac{ 1 }{ x }-\frac{ x }{ x+1 }\] The LCD is x(x+1) so \[\frac{ 1 }{ x }\left( \frac{ x+1 }{ x+1 } \right)-\frac{ x }{ x+1 }\left( \frac{ x }{ x} \right)\] Now multiply those out and simplify .... then we'll go from there.
x+1/x / xˆ2+x - xˆ2 / xˆ2 + x. is this correct?
Yes but I would leave the denominator unmultiplied for later. use...\[\frac{ x+1 }{ x \left( x+1 \right)}-\frac{ x^2 }{ x \left( x+1 \right) }\] but now combine the two fractions since they have common den.
What do you get?
x+1 - xˆ2 / x(x+1) right?
Well yes ... I thin you mean (x+1-x^2)/[x(x+1)]. I know this seems picky but the order of operations are a pretty picky on this...it is equivalent to:\[\frac{ x+1-x^2 }{ x \left( x+1 \right) }\]
Now for sake of convention I would suggest writing the terms of the numerator in descending order of power...so that would be:\[\frac{ -x^2+x+1 }{ x \left( x+1 \right) }\]
yes, I understand this
Now follow the same procedure for the fractions in the bottom of the ratio (keeping the denominator factored instead of multiplied out)
What do you get?
2xˆ2 + 2 - xˆ2 -1 / x(x+1). Is this correct?
Please not that this is written very poorly. (1/x - x/ x+1) / (2/x+1 - x-1/x) I believe you mean: (1/x - x/ (x+1)) / (2/(x+1) - (x-1)/x) That's a whole different ballpark.
@Paynesdad
I agree is the bottom of the ratio:\[\frac{ 2 }{ x+1 }-\frac{ x-1 }{ x }\]
It is not quite what you wrote at the beginning but it makes the most sense so I am assuming you forgot some parentheses.
@Paynesdad how do I continue for the down ratio? can you please help?
Is the bottom ratio the one I listed a couple of lines above? (I can't tell from your post as it seems to be missing some key parentheses.)
yes, that is the bottom ratio
Ok so what is the LCD of the bottom of the ratio then?
x+1?
Not quite x+1 is part of it but not the whole thing. Look at what you did for the top of the ratio.
x(x+1) ?
There you go so what do you need to multiply the top and bottom of the first fraction by so that it has the lcd?
x/x?
for the first fraction
yep and the second?
x+1?
well (x+1)/(x+1) yes...so go ahead and multiply those out (not the denominators though) and combine the fractions and tell me what you get.
2x/xˆ2+x - xˆ2+x/xˆ2 +2. is it correct?
No the first one is good.
Now you have\[-\frac{ \left( x-1 \right)\left( x+1 \right) }{ x \left( x+1 \right)}\] ... also don't worry about multiplying out the denominator ...it is best to just leave it "unmultiplied" (or in factored form). What does the numerator multiply to?
this is the second part of the second fraction right? because I am confused
Yes.
Ok I understand now. it the numerator 2x - (x-1)(x+1)?
yep there you go
so multiply that and simplify. what do you get?
i dont know:(
@Paynesdad
Well multiply (x-1)(x+1)... can you do that?
xˆ2-1
@Paynesdad can you please help?
yes so now you can combine the numerators of the two fractions since their denominators are the same... right?
what do you mean by combine? add them or ...?@Paynesdad
@Paynesdad
yes add, subtract them do what every the expression indicates to do.
-xˆ2+x-1 + 2x - xˆ2 -1 / x(x+1). is this correct?
whoa too much....let's back up...you had...
\[\frac{ 2x }{ x \left( x+1 \right) }-\frac{ x^2-1 }{ x \left( x+1 \right) }\] after multiplying out each fraction right?
yes
ok so when you combine those fractions you subtract the numerators and the denominator stays the same...just like fractions with numbers...so what is that
2x-xˆ2-1/ x(x+1)
good now again I would suggest putting the numerator's terms in descending power order. So
Well wait one thing ... it was 2x - (x^2-1), right?
yes
Well this why those parentheses are so important...2x-(x^2-1) does not equal 2x - x^2 -1 does it?
no, it equals 2xˆ4 -2 right?
No that s way off... remember to distribute the minus sign on the stuff in parentheses!...With \[\frac{ 2x }{ x \left( x+1 \right) }-\frac{ x^2-1 }{ x \left( x+1 \right) }\] you are not just subtracting the x^2 but x^2 and the -1! so\[\frac{ 2x }{ x \left( x+1 \right) }-\frac{ x^2-1 }{ x \left( x+1 \right) }=\frac{ 2x-\left( x^2-1 \right) }{ x \left( x+1 \right) }\] so \[\frac{ 2x }{ x \left( x+1 \right) }-\frac{ x^2-1 }{ x \left( x+1 \right) }\neq\frac{ 2x- x^2-1 }{ x \left( x+1 \right) }\] do you see what I am getting at?
@RH ?
is the answer (x-1)ˆ2 / (x+2)ˆ2
@Paynesdad
No...you seem to have gone off the tracks...let's go back to\[\frac{ 2x }{ x\left( x+1 \right) }-\frac{ x^2 -1}{ x \left( x+1 \right) }=\frac{ 2x- \left( x^2-1 \right)}{x \left( x+1 \right) }\] when you distribute the "-" sign what do you get?
-2xˆ4 + 2x? @Paynesdad
How are you getting \[-2x^4\] ???
-2xˆ3 sorry. is it correct?
@Paynesdad
No because you are not multiplying! That is subtraction so you distribute the minus sign to get\[\frac{ 2x -\left( x^2-1 \right)}{ x \left( x+1 \right)}=\frac{ 2x-x^2+1 }{ x \left( x+1 \right) }\]
Not sure why you were multiplying.
ok now I understand, sorry for my mistake. how do i continue to simplify?
:-) ok I would put the numerator in power order just for the sake of convention...so that would be\[\frac{ -x^2 +2x+1}{ x \left( x+1 \right) }\] so now lets put these back into the ratio...So we have...
-xˆ2 + x - 1/ x(x+1) divided by -xˆ2 + 2x -1/ x(x+1)
Yes! so now reciprocate the fraction in the bottom of the ratio and cancel what can be and what are you left with?
I am not sure I understand what you mean with that? :(
Ok first of all I think you have a couple of -1 that should be +1 double check that
where???? @Paynesdad
So you should have \[\frac{ \frac{ -x^2+x+1 }{ x \left( x+1 \right) } }{ \frac{ -x^2+2x+1 }{ x \left( x+1 \right) } }\] ... look closely at everything and make sure you agree
@RH
yes!!!! you are right!!! the +1! sorry
Ok so you can reciprocate the bottom of the ratio and get...
\[\left( \frac{ -x^2+x+1 }{ x \left( x+1 \right) } \right)\left( \frac{ x \left( x+1 \right) }{ -x^2+2x+1 } \right)\]
do i cancel out now the same x(x+1)?
Yep!
and how do I simplify after that?
Unless you can factor the polynomials in the numerator and denominator (which you can't) and find common factors to cancel. You are done.
I would suggest learning the proper place to put parentheses when using / instead of a fraction bar. ... i.e. \[\frac{ 3+2 }{ 4+1 }=(3+2)/(4+1)\] not 3+2/4+1 because \[3+2/4+1=3+\frac{ 1 }{ 2 }+1=4\frac{ 1 }{ 2 }\]
thanks a lot!!!
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