An=a1+d(n-1)
an=nth term
a1=first term, when n=1
d=common differnce=amount each term increases by
n=which one
so
when n=1, an=40
so a1=40
it seems to increas by 7 each time
an=40+7(n-1)
explicit formula is expanded
an=40+7n-7
an=33+7n is the formula
the domain is natural numbers because you can't have the -3rd term or the 0th term or the 3.24th term
domain is natural numbers
the formula is

or
Steps to solve:
-4z + 4 + 12z = 3z + 4 + 5z
~Combine like terms
8z + 4 = 8z + 4
~Subtract 4 to both sides
8z = 8z
~Divide 8 to both sides
0 = 0
All real numbers are solutions.
Set builder notation: {x | R}
This is an identity since every value can be a solution to the equation.
Best of Luck!
Yes 1.999 is an <span>irrational number</span>