factor completely over the integers: 121 - 64x2 - 36y2 + 96xy I've tried pairing the integers in different ways and still can't solve this. Please help. Thank you. ------------------------------------------------------------------- Sometimes pairing doesn't work and you have to try grouping three factors: 121 - 64x2 - 36y2 + 96xy Interchange the last two terms 121 - 64x2 + 96xy - 36y2 Factor -4 out of the last three terms 121 - 4(16x2 - 24xy + 9y2) Factor the expression in the parentheses 121 - 4(4x-3y)(4x-3y) This is now the difference of two perfect squares 112 - 22(4x-3y)2 [11 - 2(4x-3y)][11 + 2(4x-3y)] Remove the parentheses inside the brackets [11-8x+6y][11+8x-6y] Change the brackets to parentheses (11-8x+6y)(11+8x-6y) Edwin AnlytcPhil@aol.com