(2x+3y)² - (x-y)²
= (2x)² + 2(2x)(3y) + (3y)² - (x)² + 2(x)(y) - (y)= 4x² + 12xy + 9y² - x² + 2xy - y= 3x² + 14xy + 8y²
(2x+3y)² - (x-y)²
= (2x)² + 2(2x)(3y) + (3y)² - (x)² + 2(x)(y) - (y)
= 4x² + 12xy + 9y² - x² + 2xy - y
= 3x² + 14xy + 8y²