Question

Find the domain of the following function:

y = x^3 − 8
________
x^2 + 5x + 6

Select the appropriate response:

A) domain: x cannot equal −3, −2

B) domain: x equals −3, −2


C) None of the above

Help please! 40 points!

Answer 1

A) domain: x cannot equal −3, −2

Explanation:

y = x^3 − 8

________

x^2 + 5x + 6

The function is undefined when the denominator goes to zero

x² + 5x + 6 = 0

x² + 3x + 2x + 6 = 0

x(x + 3) + 2(x + 3) = 0

(x + 2)(x + 3) = 0

x = -3, -2

Domain can take any value except -2 and -3

Answer 2

The answer is C.

Explanation:

You can do it by solving both equations :

y = x³ - 8

Let y=0,

x³ - 8 = 0

x³ = 8

x = ³√8

= 2

x² + 5x + 6 = 0

(x+3)(x+2) = 0

x = -3

x = -2

So the domain for 1st equation is 2 and 2nd equation is -2 & -3.

In 1st equation, the answer cannot be option A & B and in 2nd equation, the answer is B.