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Mathematics 17 Online
OpenStudy (airyana1114):

I need help with finding the simplified form of an equation.

OpenStudy (airyana1114):

\[ \frac{ 1 }{ x } - \frac{ 2 }{ x^{2}+ x }\]

OpenStudy (danjs):

to combine the two, need to change to same denominators

OpenStudy (danjs):

x^2 +6 x = 2z + 6 for

OpenStudy (airyana1114):

I'm sorry where did the 6 and z come from?

OpenStudy (alexandervonhumboldt2):

like dan said, equal the denominators

OpenStudy (mathmale):

Please look at the expression you've typed in, and determine what the lowest common denominator (LCD) is. You'll need the LCD to combine those two fractions into one.

OpenStudy (alexandervonhumboldt2):

hint: x^2+x=x*(x+1)

OpenStudy (mathmale):

To find the LCD, you could multiply the two given denominators together. but Alex has a better idea: He sees that the two given denominators share a common factor, which is x. The den. of the second fract. is done (although it'd look nicer if you factor it as Alex has done). What do y ou have to do to the 1st fraction to obtain the same LCD in the denominator? Hint: You must multiply its numerator and its denom. by the same thing.

OpenStudy (airyana1114):

I'm not sure what I would do, all I know is that I need to get \[x^{2}\] into my first denominator.

OpenStudy (mathmale):

It's more than just x^2. If done correctly, your numerator in the first fraction will become a polynomial in x.

OpenStudy (mathmale):

Note that you have "x" in the denom. of the first fraction. Multiply that x by ... what? ... so that you have the LCD in BOTH fractions.

OpenStudy (airyana1114):

by two?

OpenStudy (mathmale):

First, type in the LCD. See Alex's work (above). Second, determine by what quantiity you must multiply the x in the denom. of the 1st question to get the LCD there.

OpenStudy (airyana1114):

So my denominator's would be x(x + 1)?

OpenStudy (airyana1114):

To get that for my first denominator I need to multiply x by (x + 1), correct?

OpenStudy (mathmale):

yes, very good. if you mult

OpenStudy (mathmale):

the den. of the 1st fract. by x+1, you must also mult. the num. by the same quantity. Do this and type in your results, please.

OpenStudy (mathmale):

Thus, \[\frac{ 1 }{ x }+\frac{ 2 }{ x^2+x }becomes. what?\]

OpenStudy (airyana1114):

would my x^2 + x become x(x + 1) as well?

OpenStudy (mathmale):

The second fraction doesn't change, unless y ou wish to factor the denom. (which looks better). The first fraction becomes

OpenStudy (mathmale):

\[\frac{ x+1 }{ x(x+1) }\]

OpenStudy (mathmale):

And now the fractions have the same denominator.

OpenStudy (airyana1114):

Okay, so then what happens with my second numerator?

OpenStudy (mathmale):

Nothing. No need to change it, because the denom of that fraction is already the LCD. Now combine those two fractions, now that they have the same denom. This requires that y ou add together the numerators. Be careful with signs.

OpenStudy (airyana1114):

Okay so I first changed my denominators to x(x + 1), then I change my first numerator by multiply it by (x + 1) which gives me \[\frac{ x+1 }{ x(x+1) }\] and then I just subtract my second numerator from my first correct? Since in my original equation I was subtracting?

OpenStudy (airyana1114):

Which leaves me with x-1 over x(x+1)

OpenStudy (mathmale):

Great job!!!!

OpenStudy (airyana1114):

:) thank you!

OpenStudy (mathmale):

Hope you'll review our discussion so that you can apply this procedure to solving similar problems in the future. You're welcome!!

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