Ask a question

exponential function #2

evaluate the exponential function at the specified value of x
f(x)=4x,  x= -4

2 Answers by Expert Tutors

Tutors, sign in to answer this question.
Jose S. | Friendly Mathematics, Philosophy, and Computer Science tutorFriendly Mathematics, Philosophy, and Co...
Hey Carlos
You need to think about the rules for exponents. Is there any that tells you how to deal with negative exponents?

Here is a way to think about it.  For positive exponents you could write x^n = x*x^(n-1), as long as n is greater than 0.  This can be rewritten as: x^(n-1) = (x^n)/x, as long as x is not 0.  Now suppose n is 0, and the rule gives us: x^(-1) = x^(0)/x.  Since x^0 is 1, this means x^(-1) = 1/x.  If we assume this holds as long as n is an integer(positive or negative) and x is not 0, then we have that x^(-2) = x^(-1)/x = ([x^0]/x)/x =(1/x)/x = 1/x^2, and in general x^(-n) = 1/(x^n).  Then in your case, 4^(-4) = 1/(4^4).

From here just multiply to find: 1/(4*4*4*4)=?
Hope this is helpful,
5.0 5.0 (430 lesson ratings) (430)
f(x) = 4x
f(x=4) = 44 = 4*4*4*4 = ??


I'm sorry Philip I'm still confused....what happened to the -4?  And what are the powers to the 4...please help, I'm confused