Выражение: 1) (12a-b)^2 - (9a-b)(16a+2b) 2) x(2x-9)^2 - вопрос №77415611122916222922152308 от elektroo67 20.04.2020 02:18

Question

Алгебра: Выражение: 1) (12a-b)^2 - (9a-b)(16a+2b) 2) x(2x-9)^2 - 2x(15+x)^2 3) 0,8(xy-2)^2 + 1,2(xy-1)^2 4) (x+2)^2 - (x-3)(x+3) 5) (7a-5b)(7a+5b) - (4a+7b)^2 6) (y-2)(y+3) - (y-1)^2 + (5-y)(y+5) ! заранее большое !

elektroo67 · Answer

1) = 144а^2 - 24ab + b^2 - (144a^2 - 16ab +18ab - 2b^2) =
= 144a^2 - 24ab + b^2 - 144a^2 + 16ab - 18ab + 2b^2 =
= 3b^2 - 26ab

2) = x(4x^2 -36x + 81) - 2x(225 + 30x + x^2) =
= 4x^3 - 36x^2 + 81x - 450x - 60x^2 - x^3 =
= 3x^3 - 90x^2 - 369x

3) = 0,8(x^2y^2 - 4xy + 4) + 1,2(x^2y^2 - 2xy + 1) =
= 0,8x^2y^2 - 3,2xy + 3,2 + 1,2x^2y^2 - 2,4xy + 1,2 =
= 2x^2y^2 - 5,6xy + 4,4

4) = x^2 + 4x + 4 - (x^2 - 3^2) =
= x^2 + 4x + 4 - x^2 + 81 = 4x + 85

5) = (7a)^2 - (5b)^2 - (16a^2 + 56ab +49b^2) =
= 49a^2 - 25b^2 - 16a^2 - 56ab - 49b^2 =
= 33a^2 - 74b^2- 56ab

6) = y^2 - 2y + 3y - 6 - (y^2 -2y +1) + (5y - y^2 + 25 - 5y) =
= y^2 + y - 6 - y^2 + 2y - 1 - y^2 + 25 =
= - y^2 + 3y + 19