Question

The function ƒ(x)=a^x+4 will never cross the x-axis.
A. True
B. False

Answer 1

True

Answer 2

Have you tried graphing this for various values of a?

Geogebra can do this quickly and easily. (and freely).

Answer 3

thank you, and yes i did i just didnt know if that was how to actually do it or not

Answer 4

http://www.wolframalpha.com/input/?i=plot+y%3D5%2C+y%3D2^x%2B4%2Cy%3D3^x%2B4%2Cy%3D4^x%2B4

Answer 5

If you try solving 0 = a^x + 4 for x

You will have log base a of -4 = x

But you can't have a negative base to a logarithm. (that's how it's defined. :)

Answer 6

You can have negatives in a log :P (digresses)

Answer 7

True true. But we want the log function to be single-valued and return a real result. :)

Answer 8

Yeap :P