Question

Expand the following:

(3x³ − 8y²)²

Answer 1

(3x³ − 8y²)²

Using the identity:

(a − b)² = a² − 2ab + b²

Here, let a = 3x³, b = 8y²

(3x³ − 8y²)² = (3x³)² − 2(3x³) (8y²) + (8y²)² 

= 9x⁶ − 2(24x³y²) + 64y⁴

∴ (3x³ − 8y²)² = 9x⁶ − 48x³y² + 64y⁴