To collect like terms, we need to combine the coefficients of the same powers of \( x \). In this case, we have terms with \( x^3 \) and \( x^2 \). We will sum the coefficients of \( x^3 \) and \( x^2 \) separately.
Step 1: Combine Like Terms for \( x^3 \)
We start with the terms involving \( x^3 \):
\[
\frac{1}{4} x^3 + \frac{3}{8} x^3 + \frac{1}{16} x^3
\]
Calculating the coefficients:
\[
\frac{1}{4} + \frac{3}{8} + \frac{1}{16} = \frac{11}{16}
\]
Thus, the combined term for \( x^3 \) is:
\[
\frac{11}{16} x^3
\]
Step 2: Combine Like Terms for \( x^2 \)
Next, we combine the terms involving \( x^2 \):
\[
-x^2 - \frac{1}{6} x^2
\]
Calculating the coefficients:
\[
-1 - \frac{1}{6} = -\frac{6}{6} - \frac{1}{6} = -\frac{7}{6}
\]
Thus, the combined term for \( x^2 \) is:
\[
-\frac{7}{6} x^2
\]
Step 3: Write the Final Expression
Combining both results, we have:
\[
\frac{11}{16} x^3 - \frac{7}{6} x^2
\]