Question

g(x)=x^2+x-72/x^2-8x+7 find all values of x that are not in the domain for g

Answer 1

x^2-8x+7
x^2-7x-1x-7
x(x-7)-1(x-7)
(x-7)(x-1)

x cannot equal 1
x cannot equal 7

Answer 2

... which means that at these two points, there will be a vertical asymptote and g(x) is not defined (only) at theses two points.

Answer 3

i get that it is undefined but what would i do to find x=?

Answer 4

Hero just did it before I had a chance! x is undefined at x=1 and x=7, these are the values which makes the denominator zero, and hence g(x) is undefined at these two points.

Answer 5

so the x= 1,7,....

Answer 6

or just simply x=1,7

Answer 7

Almost, just skip the "..." because there are only two points which make g(x) undefined. A polynomial is defined from -inf to +inf. When it is a rational function (i.e. divided by another polynomial), we need to check for zeroes of the denominator. Where the denominator vanishes, the function is undefined.
In this case, the denominator vanishes at x=1 and x=7 and no other place. So there are only two points (between -inf and +inf ) which are undefined.

Answer 8

aww ok thank ya so much

Answer 9

You're welcome!