Chapter 11 - Rational Expressions and Functions - 11-2 Multiplying and Dividing Rational Expressions - Practice and Problem-Solving Exercises - Page 676: 71

$2x+3$

Let $w$ be the width. Thus, $4x^{3}+6x^{2}=2x \times x \times w$ (Volume = length $\times$ width $\times$ height) Hence, $w = \frac{4x^{3}+6x^{2}}{2x^{2}}=\frac{2x^{2}(2x+3)}{2x^{2}}$ $w=2x+3$ (After dividing out the common factor $2x^{2}$)