Problem
ALG-B1-M01-P002 Sum of Cubes
#2
★☆☆☆☆ Level 1 of 5
Factor \(8a^3+27b^3\).
Write the expression as \((2a)^3+(3b)^3\).
Use \(u^3+v^3=(u+v)(u^2-uv+v^2)\), with \(u=2a\), \(v=3b\).
Thus \(8a^3+27b^3=(2a+3b)(4a^2-6ab+9b^2)\).
The sign of the middle term is the main point.