Which of the following is not a rational expression?

5x

2x^2/11

5x/x+2

1/x^2+11x+30

Question

Which of the following is not a rational expression?

5x

2x^2/11

5x/x+2

1/x^2+11x+30

ganeshie8 · Answer

last expression, is that

1/x^-1 + 11x + 30

 ?

anonymous · Answer

oh, i meant 1/x^2+11x+30

ganeshie8 · Answer

ohhk to my knowledge all options are rational expressions as all can be written of the form p/q. pls wait and see what others say :D

anonymous · Answer

okay, because one of them can't be

asnaseer · Answer

a rational expression is any expression that can be written in the form p/q.

however, note that the denominator cannot equal zero.

asnaseer · Answer

so, if for any of them you can think of a value for x that would make the denominator zero, then that expression is not rational

anonymous · Answer

im not sure which one

asnaseer · Answer

sorry - what I meant to say is that they ARE all rational, but some of them need to have conditions applied to them

asnaseer · Answer

to avoid the division by zero

anonymous · Answer

so what do i need to do?

asnaseer · Answer

e.g. for the 3rd one, x cannot equal -2

asnaseer · Answer

and for the last one:$$x^2+11x+30=(x+5)(x+6)$$so x cannot equal -5 or -6

anonymous · Answer

well then how would i figure out which one it is then?

asnaseer · Answer

so they are ALL rational expressions with the conditions added for the 3rd and 4th one

anonymous · Answer

which one should i got with then?

asnaseer · Answer

ALL

anonymous · Answer

i can only pick one

asnaseer · Answer

ALL are rational.

Question asks which one is NOT rational - so I would say NONE of them is NOT rational

anonymous · Answer

i know, its multiple choice so i have to pick an answer

asnaseer · Answer

this might help you: http://tutorial.math.lamar.edu/Classes/Alg/RationalExpressions.aspx

asnaseer · Answer

this might be easier to understand: http://www.mathsisfun.com/algebra/rational-expression.html

asnaseer · Answer

are you SURE you have listed the 4 options correctly?

anonymous · Answer

ill repost them just in case.

anonymous · Answer

5x, 2x^2/11, 5x/x+2, 1/x^2+11x+30

asnaseer · Answer

so these are the options?$$a) 5x$$$$b)\frac{2x^2}{11}$$$$c)\frac{5x}{x+2}$$$$d)\frac{1}{x^2+11x+30}$$

anonymous · Answer

yes

asnaseer · Answer

well, I would still say that they are ALL rational expressions (with the conditions applied to (c) and (d) that I showed above). 

so maybe they made a mistake in the list given to you?

asnaseer · Answer

or maybe I am missing something? :)

anonymous · Answer

im not sure..