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Mathematics 15 Online
OpenStudy (anonymous):

HELP!(: Find any points of discontinuity for the rational function. y= (x+6)(x+2)(x+8)/(x+9)(x+7)

OpenStudy (ash2326):

Here We've \[y=\frac{(x+6)(x+2)(x+8)}{(x+9)(x+7)} \] @Math4Life What is a discontinuity ? What do you think y is when x=-8?

OpenStudy (anonymous):

I just solved and got the answer as x = –6, x = –2, x = –8

OpenStudy (ash2326):

Oh these won't be discontinuities, y is zero which is finite. Zeros doesn't count as discontinuities. Find values of x which makes difficult to evaluate y or y cease to exist

OpenStudy (anonymous):

@ash2326 u rigth!

OpenStudy (anonymous):

@ash2326 I solved and got x = –6, x = –2, x = –8 am I correct or no?

OpenStudy (ash2326):

No x=-6 y=0 which is finite, we didn't have any difficulty in evaluating this and so for x=-2 and x=-8. Try to find x which will make us worry!!!! Answer is in the question

OpenStudy (anonymous):

Hint: 1/0 is undefined.

OpenStudy (ash2326):

ok @Math4Life I'll give you a hint What's this? \[\huge \frac{1}{0}\]

OpenStudy (anonymous):

x=-9 and x=-7 are the only points of discontinuities

OpenStudy (anonymous):

What values will make the denominator 0? Those are the values where there will be discontinuities.

OpenStudy (anonymous):

@ash2326 wait so whats the answer? sorry like I said I was gone

OpenStudy (anonymous):

@ash2396 is it x=-9 x=-7?

OpenStudy (ash2326):

See my previous post:) Can you create that type of condition here?

OpenStudy (anonymous):

@ash2326 is it x=-9 x=-7?

OpenStudy (ash2326):

How did you get this?

OpenStudy (anonymous):

@ash2326 @eliassaab said so

OpenStudy (anonymous):

A rational function is contniuous everwhere except for points that make the denominator zero

OpenStudy (ash2326):

@Math4Life just answers won't help. Try to arrive by yourself. If you need any explanation I'm here

OpenStudy (anonymous):

everywhere

OpenStudy (anonymous):

What's a discontinuity? An asymptote?

OpenStudy (anonymous):

@ash2326 Ya I know what your saying I'm just a little confused

OpenStudy (anonymous):

@ash2326 I think thats the right answer and if it is can u explain to me how it is?

OpenStudy (ash2326):

Okay:)

OpenStudy (anonymous):

Rational functions always have a point where they cannot cross called an "asymptote" To find it, set your denominator terms to zero.

OpenStudy (ash2326):

@Math4Life Suppose we have a function y given as \[y=\frac{x-1}{x}\] as we notice if x=1, numerator is zero. \[y=\frac{0}{1}=0\] that's easy to find. No problem at all.:D:D If we try to plot the graph of y versus x. Then we'll put values of x and find y. It's easy but we don't know about the problem we could face:P

OpenStudy (anonymous):

Also remember, in this case, there is a possibility of an oblique asymptote also. To find it, divide your numerator by your denominator.

OpenStudy (anonymous):

The quotient will be the oblique asymptote, the remainder will be the distance from the asymptote.

OpenStudy (anonymous):

I understand now I just asked a friend

OpenStudy (anonymous):

Thanks for all your help people!

OpenStudy (ash2326):

@Math4life The most dreadful point is x=0, which will make \[y=\frac{-1}{0}\] We can't find its value this is undefined:(:(

OpenStudy (anonymous):

See the graph. It confirms that the points of discontinuities are x =-9 and x=-7

OpenStudy (ash2326):

@Math4Life now in our question, There are two values of x which will make y undefined. Can you find those two xs?

OpenStudy (anonymous):

@ash2326 I understand this now I just talked to a friend over the phone, thanks for all ur help!

OpenStudy (anonymous):

Don't forget to find those obliques also.

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