The answer is 5.1 when you enter it into a calculator :)
If you would like to know if (3, 6) is a solution to the inequality x + y <= 9, you can calculate this using the following steps:
(3, 6) ... x = 3, y = 6
x + y <= 9
3 + 6 <= 9
9 <= 9
Result: (3, 6) is a solution to the inequality x + y <= 9.
N(2n+6)-(n²-1)= 2n²+6n-n²+1=n²+6n+1
