Intermediate Algebra, Chapter 5, 5.2, Section 5.2, Problem 74

Add: $(-6m^3 + 2m^2 + 5m) + (8m^3 + 4m^2 - 6m) + (-3m^3 + 2m^2 - 7m)$

Remove the parentheses that are not needed from the expression.
$-6m^{3}+2m^{2}+5m+8m^{3}+4m^{2}-6m-3m^{3}+2m^{2}-7m$


Since $-6m^3$ and $8m^3$ are like terms, subtract $8m^3$ from $-6m^3$ to get $2m^3$
$2m^{3}+2m^{2}+5m+4m^{2}-6m-3m^{3}+2m^{2}-7m$


Since $2m^3$ and $-3m^3$ are like terms, add $-3m^3$ to $2m^3$ to get $-m^3$
$-m^{3}+2m^{2}+5m+4m^{2}-6m+2m^{2}-7m$


Since $2m^2$ and $4m^2$ are like terms, add $4m^2$ to $2m^2$ to get $6m^2$
$-m^{3}+6m^{2}+5m-6m+2m^{2}-7m$


Since $6m^2$ and $2m^2$ are like terms, add $2m^2$ to $6m^2$ to get $8m^2$
$-m^{3}+8m^{2}+5m-6m-7m$


Since $5m$ and $-6m$ are like terms, add $-6m$ to $5m$ to get $-m$.
$-m^{3}+8m^{2}-m-7m$


Since $-m$ and $-7m$ are like terms, subtract $7m$ from $-m$ to get $-8m$.
$-m^{3}+8m^{2}-8m$