(x + 3)(4x + 3) = 4x² + 3x + 12x + 9 = 4x² + 15x + 9
(x − y)(4x − y) = 4x² - xy - 4xy + y² = 4x² - 5xy + y²
(2 + x)(2 − x) = 4 - 2x + 2x - x² = -x² + 4
(2 + k)(1 − m) = 2 - 2m + k - km = -2m + k - km + 2
(x − 2)(3x - 2) = 3x² - 2x - 6x + 4 = 3x² - 8x + 4
(−a + 2c)(4a + c) = -4a - ac + 8ac + 2c² = -4a + 7 ac + 2c²
(5x – 10) : 5 = x - 2
(4x² – 8x) : 4 = x² - 2x
