Question

СРОЧНО!!!!! Даю 40 баллов!!!!!!

Answer 1

Ответ:

Объяснение:

1) $(2a^{2} - 3a +1) - (7a^{2} - 5a) = 2a^{2} - 7a^{2} - 3a +5a +1 = -5a^{2} + 2a +1$

2)$3x(4x^{2} -x) = 12x^{3} - 3x^{2}$

3)$(a-5)(a-3) = a^{2} - 3a -5a + 15 = a^{2} - 8a + 15$

4)$(5x+4)(2x-1) = 10x^{2} - 5x +8x - 4 = 10x^{2} + 3x - 4$

5)$(6-2)(b^{2} + 2b - 3) = 4b^{2} + 8b - 12$

6) $7 -4(3x - 1) = 5(1-2x)\\7 - 12x + 4 = 5 - 10x\\3-12x = 5 - 10x\\-2 = 2x\\x=-1$

7)$(2-x)^{2} + x (x+1.5) = 4 \\ 4 - 4x + x^{2} + x^{2} + 1.5x = 4\\2x^{2} - 2.5x = 0\\x(2x-2.5) = 0\\x=0\\2x-2.5 = 0\\x = 1.25$

8)$3x(x + y + c) -3y(x -y - c) - 3c(x + y - c) = \\=3x^{2} + 3xy + 3xc - 3yx + 3y^{2} + 3yc - 3 cx - 3 yc + 3 c^{2} = \\= 3 x^{2} + 3y^{2} + 3c^{2} = 3(x^{2} +y^{2} +c^{2} )$