Question

СРОЧНО ДАЮ 100 БАЛОВ​

Answer 1

Объяснение:

$(x+a)(x+b) = x^2 +bx + ax + ab = x^2 + (a+b)x + ab\\(x-y)(x+y) = x^2 - y^2\\(x+y)^2 = x^2 + 2xy + y^2\\(x-y)^2 = x^2 - 2xy + y^2$

$1) (x+3)(x-7) -4x(5-2x) = x*x + x*(-7) + 3 * x + 3 * (-7) - 4x * 5 -4x * (-2x) = x^2 - 7x + 3x -21 -20x + 8x^2 = 9x^2 -24x - 21$

$2) (y+2)(y-6) + (y+3)(y-4) = y^2 -6y + 2y -12 + y^2 -4y + 3y - 12 = 2y^2 - 5y - 24$

$4) (x+4)^2 - (x-2)(x+2) = (x+4)^2 - (x^2 - 4) = x^2 + 8x + 16 - x^2 + 4 = 8x + 20$

$5) (8a - 3b)(8a + 3b) - (6a - 5b)^2 = 64a^2 - 9b^2 - (36a^2 - 60ab + 25b^2) = 64a^2 - 9b^2 - 36a^2 + 60ab - 25b^2 = 28a^2 + 60ab - 34b^2$