Algebra: A Combined Approach (4th Edition)

$h(x) = \big(\frac{1}{2}x\big)^2$ is not an exponential function.
$h(x) = \big(\frac{1}{2}x\big)^2 = \big(\frac{1}{2}\big)^2\big(x\big)^2 = \frac{1}{4}x^2$ This function is a quadratic function (the variable $x$ is raised to the power of $2$), not an exponential function, it does not have the form $h(x)=b^x$.