Answer:
[tex]-\sqrt{14} < c < \sqrt{14}[/tex]
Step-by-step explanation:
For the function to have a domain of all reals, the denominator cannot have a value of zero. x^2 + 2cx + 14 will not have zero as a root if it has no real solutions. A quadratic equation has no solutions when the discriminant is negative.
b^2 - 4ac < 0
(2c)^2 - 4(1)(14) < 0
4c^2 - 56 < 0
4c^2 < 56
c^2 < 14
[tex]-\sqrt{14} < c < \sqrt{14}[/tex]
