126 is a term in the sequence. Please check my assumption on the correct formula.
Step-by-step explanation:
I will assume that n2 + 5 is actually n^2 + 5.
Starting with n=0, use the formula to calculate successive values of n. The attached table is the result of n from 0 to 22. At n=11, the result is 126, so 126 is a term in the sequence.
If the expression is actually n2 + 5, calculate the values for y = 2n + 5. 126 would not be a term in this sequence.
In this case, since one equation is in the form of x=, substitution would be best for this problem. Simply plug in 4y + 8 in place of x in the second equation, solve for y, then plug that value into the first equation to find x.