1.) Simplify. x/6x-x^2

A. 1/6-x; where x ≠ 0, 6
B. 1/6-x; where x ≠ 6
C. 1/6x; where x ≠ 0
D. 1/6

2.) Simplify. -12x^4/x^4+8x^5

A. -12/1+8x; where x ≠ -1/8
B. -12/1+8x; where x ≠ -1/8, 0
C. -12/9x; where x ≠ 0
D. -12/9

How do I find what x ≠ ?

2 answers

since division by zero is undefined, x cannot be any value that makes the denominator zero.
Question 1 is b, correct?