If f is a linear function such that f(-1) = 5 and f(2) = -1,then f(x + 1) = ?

You should notice that the function is linear, hence,
substituting x+1 for x in equation of a linear function
yields:

n

Substituting -1 for , or , in equation
above yields:

n

Substituting 2 for , or , in equation
above yields:

-1

Subtracting the equation   from  
yields:

2m+n+m-n=-1-5 => 3m = -6 => m =
-2

Substituting -2 for m in equation -m+n=5 yields
=gt n=5-2 =gt n=3

1

Hence, evaluating the equation of linear
function yields