## Introductory Algebra for College Students (7th Edition)

Write the distribution as the sum of two products, and then simplify: $3(5x+7)=3\cdot 5x+3\cdot 7$ and then simplify to $15x+21$
The student forgot to distribute the 3 to the second term in the parentheses. To avoid this error, maybe it's best to write the distribution as the sum of two products, and then simplify: $3(5x+7)=3\cdot 5x+3\cdot 7$ and then simplify to $15x+21$