Here the only limitation on the domain exists when the denominator is equal to zero, as division by zero has no meaning and is not "allowed" because of its meaninglessness. :)
Factor the denominator to find the excluded values of x...
3x^2+5x-12
3x^2+9x-4x-12
3x(x+3)-4(x+3)
(3x-4)(x+3)
So x CANNOT equal 4/3 or -3 (all other real values of x are part of the domain) so the domain is:
x=(-oo, -3),(-3, 4/3),(4/3, +oo)
picture one x=8 and y=4
picture two x=-18 and y=-10
picture three x=7 and y=8
give me 5 stars so i will get a crown
Answer: The mean number of checks written per day 
Standard deviation
Variance 
Step-by-step explanation:
Given : The total number of checks wrote by person in a year = 126
Assume that the year is not a leap year.
Then 1 year = 365 days
Let the random variable x represent the number of checks he wrote in one day.
Then , the mean number of checks wrote by person each days id=s given by :-

Since , the distribution is Poisson distribution , then the variance must equal to the mean value i.e. 
Standard deviation : 