a) эту подробно, остальные аналогично: (x+1)(x+2)-(x-3)(x+4)=6(x*x + x*2 + 1*x + 1*2) -(x*x + 4*x - 3*x - 12) = 6(x² + 3x + 2) -(x² + x - 12) = 6x² + 3x + 2 - x² - x + 12 = 62х = -8х = -4б) (3x-1)(2x+7)-(x+1)(6x-5)=7 6x² + 19x - 7 - 6x² - x + 5 = 718x = 9x = 1/2в) 24-(3y+1)(4y-5)=(11-6y)(2y-7)24 = (11-6y)(2y-7) +(3y+1)(4y-5)(3y+1)(4y-5) + (11-6y)(2y-7) = 2412y² - 11y - 5 + 64y - 77 - 12y² = 2453y = 106y = 2г) (6y+2)(5-y)=47-(2y-3)(3y-1)(6y+2)(5-y) +(2y-3)(3y-1) = 47-6y² + 28y + 10 + 6y² - 11y + 3 = 4717y = 34y = 2