how to solve f(-3)=-8

Question

how to write a function rule and find function values for zero.

Answer 1

There are many functions that have the property that f(-3) = -8.  This just says that if you put the number -3 into the function then you get the number -8 out.  One such function rule would be to subtract 5 from the input number, since 

-3 - 5 = -8.  This function rule is written as 

 

f(x) = x - 5

 

You can check that f(-3) = -3 - 5 = -8, and you can calculate 

 

f(0) = 0 - 5 = -5