Question

Find the domain of the rational expression: 4-x/3x+21

Answer 1

(4-x) /(3x+21)

The denominator cannot be zero

3x + 21 ≠ 0

3x ≠ -21

x ≠ -7

The domain of the function will be all real number except -7

{x | x ≠ -7}