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