(x - 6y)(x + 6y) + 9(2y)²= x² + 6xy - 6xy - 36y² + 36y² + 36y²= x² + 36y² + 36y²= x² + 72y²
4*(3x - 2y) + 8y= 12x - 8y + 8y= 12x
6xy - (x + 3y)²= 6xy - (x² + 6xy + 9y²)= 6xy - x² - 6xy - 9y²= -x² - 9y²
(a + 8b)(-a + 8b) - 4(4b)²= -a² - 8ab + 8ab + 64b² - 16b²= -a² + 48b²
(x - 6y)(x + 6y) + 9(2y)²
= x² + 6xy - 6xy - 36y² + 36y² + 36y²
= x² + 36y² + 36y²
= x² + 72y²
4*(3x - 2y) + 8y
= 12x - 8y + 8y
= 12x
6xy - (x + 3y)²
= 6xy - (x² + 6xy + 9y²)
= 6xy - x² - 6xy - 9y²
= -x² - 9y²
(a + 8b)(-a + 8b) - 4(4b)²
= -a² - 8ab + 8ab + 64b² - 16b²
= -a² + 48b²