2n+5
80 + n^2
31 plus n
n + 2
If you mean 2n+4, or 2n-4, that already is an algebraic expression. The idea might be to put it into words. 2n+4 is twice n, increased by 4. Notice you need a comma because if you write twice n increased by 4 this is 2(n+4)
-8 + 13/N, where N ≠0.
4*(n + 2)
The odd numbers 1 3 5 7 are increased by 11 each time While the even numbers 2 4 6 are halved each time. I guess you could write the sequence like this: S(n) = If n odd, then (n+3)*11; If n even, then n/2
+2
18 + n*(-2) = 18 - 2n
11 + (n/2) = 77 Subtract 11 from both sides: n/2 = 66 Multiply both sides by 2: n = 132
ab increased by 2