Question

Determine the values for x that make the rational expression undefined:

x^2+10x+17
_____________
x^2-x-20

Answer 1

Find values that make x^2-x-20=0. Factoring works. (x-5)(x+4)=0 So what numbers can you put in for the x's to make this equation true?

Answer 2

positive 5 and negative 4

Answer 3

just positive 5 works

Answer 4

Yep, so the function is undefined at x=5 and x=-4. Do you know why?

Answer 5

the denominator can not be zero

Answer 6

or negative

Answer 7

Yes. -4 also makes it =0

Answer 8

thank you

Answer 9

OK if denomintor is negative. Just can't divide by 0

Answer 10

ok