Question

Which graph represents an exponential function?
On a coordinate plane, a curve decreases rapidly and then levels out.
On a coordinate plane, a curve decreases, changes directions, and then decreases again.
On a coordinate plane, 2 curves mirror each other.
On a coordinate plane, a line curves increases gradually.

Answer 1

The first one: "a curve decreases rapidly and then levels out."

Reason: an exponential decay (y = a·b^x with 0 < b < 1) is monotonic, falls quickly for small x and approaches a horizontal asymptote (levels off). The second (changes direction) has local extrema so is not exponential, the third (two mirror curves) suggests symmetry not typical of a single exponential, and the fourth (just increases gradually) fits a linear or logarithmic shape rather than the rapid-then-faster change of an exponential.