Find f(-) if f(n) = 5n + 6.

Question

 I am learning about Function Notation and I don't get how to solve this problem.

Answer 1

I'm not sure what f(-) is.  I think you left out the actual number, but here's how it works.

 

If:           f(n) = 5n + 1

Then:      f(-1) = 5·(-1) + 1 = -5 + 1 = -4

 

Just replace the n with -1 and compute the value. If it's f(2), replace the n with 2.  Remember that 5n is 5 times n, so if you replace n with an actual number, it's 5 times that number.