Question

A sequence is defined recursively using the formula f(n + 1) = f(n) – 5 . Which sequence could be generated using this formula?

1, –5, 25, –125, ...
2, 10, 50, 250, ...
3, –2, –7, –12, ...
4, 9, 14, 19, ...

Answer 1

In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another fixed number, the base b, must be raised, to produce that number x.

Answer 2

Answer: Choice (3) which is the sequence –2, –7, –12, ...

Here we start with -2 and subtract off 5 each time we need a new term

-2-5 = -7

-7-5 = -12

and so on.

The notation f(n+1) = f(n) - 5 tells us "subtract 5 from the nth term, called f(n), to get the next term f(n+1)"