Chapter 11 - Rational Expressions and Functions - 11-4 Adding and Subtracting Rational Expressions - Practice and Problem-Solving Exercises - Page 675: 20

$35b^3c$

To find the LCD, or the Least Common Multiple,we must write out each as products of prime factors. $5b = 5 \times b$ $7b^3c = 7 \times b \times b \times b \times c$ The Least Common Multiple, or LCD, then is $5\times 7\times b\times b\times b\times c= 35b^3c$