Ответ:

(х-2)²=x²-2x-2x+4=х²-4х+4

(3m+9n)²=9m²+27mn+27mn+81n²=9m²+54mn+81n²

(c+8)(c-8)=c²+8c-8c-64=c²-64

(2a+5b)(5b-2a)=25b²-10ab+10ab-4a²=25b²-4a²

100-a²=(10-a)(10+a)

36y²-49=(6y-7)(6y+7)

16a²-24ab+9b²=(4a-3b)²

(m-1)(m+1)-(m-3)²=m²-1-(m²-6m+9)=m²-1-m²+6m-9=6m-10

(2x+5)(x-6)+2(3x+2)(3x-2)=5(2x+1)²+11

2x²+5x-12x-30+2(9x²-4)=5(4x²+4x+1)+11

2x²-7x-30+18x²-8=20x²+20x+5+11

20x²-7x-38=20x²+20x+16

20x²-20x²-7x-20x=38+16

-27x=54

x=54÷(-27)

x=-2

Объяснение: