Homework Help

(5x+3/x)-(x-1/2x)

user profile pic

vennetti | Student, Grade 11 | eNotes Newbie

Posted March 1, 2009 at 10:46 AM via web

dislike 0 like

(5x+3/x)-(x-1/2x)

3 Answers | Add Yours

user profile pic

kmieciakp | High School Teacher | (Level 1) Valedictorian

Posted March 1, 2009 at 11:40 AM (Answer #1)

dislike 0 like

Either:

[(5x+3)/x] - [(x-1) / 2x] 

adjust with common denominator, 2x:

(10x + 6)/2x - [(x-1)/2x]

distribute the negative:

10x + 6/2x + [(-x+1)/2x]

solve:

10x +6/2x + (1-x)/2x

10x + 6 +1 -x /2x

9x +7 /2x

4.5 + 3.5x

--------------------------------

OR

[(5x) +3/x] - [(x)-1/2x)]

distribute the negative:

5x +3/x + (-x) + 1/2x

common denominator 2x:

10x^2/2x +6/2x + (-2x^2)/2x + 1/2x

solve:

[10x^2 + 6 + (-2x^2) + 1] / 2x

(8x^2 + 7) / 2x

(8x^2 /2x ) + 7/2x

4x + 3.5x

x(4+3.5)

7.5x

 

 

user profile pic

neela | High School Teacher | (Level 3) Valedictorian

Posted June 10, 2009 at 11:54 PM (Answer #2)

dislike 0 like

(5x+3/x)-(x-1/2x) :

In mathematics the first bracket is only decorative.

(5x+3/x) =5x+(3/x). And cannot mean (5x+3)/x.

-(x-1/2x) = -x+(1/2)x, and cannot mean (x-1)/(2x). 1/2x is not 1/(2x) but it means (1/2)x.

 

Therefore

5x+(3/x)-x+(1/2)x =5x-x+(1/2)x+(3/x)

=(5-1+0.5)x+3/x = 4.5x+3/x

*---*--------*-----------*

If you wanted the factors:The expression is equal to  (1/x)(4.5x^2 +3)  or  (2/x)(9x^2 +6) .

If you wanted to solve for zeros:

No real solution and Y axis is an asymptote.

y=4.5x is another obleque asynptote.

The expression is discontinuous at x= 0 with an infinite jump from positive infinity to negative infinity as x change sign around zero i.e from  0+  to  0- .

 

user profile pic

popocatepetl | College Teacher | eNotes Newbie

Posted October 22, 2009 at 1:19 PM (Answer #3)

dislike 0 like

multiply top and bottom of the 1st fraction by 2 to match denominators & get

(10x + 6) /2x   now rewrite the numberator to match the numerator of the second fraction so that you get

( 9x+x-1+7 ) /2x  - ( x-1 )/2x )

Now write the difference of the numerators over 2x to get

( 9x+7 ) / 2x

 

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes