1.
x+2≠0
x≠2
(-∞;2)∨(2; +∞)
2.
...= (a+b)(a+b) / (a-b)(a+b) = a+b / a-b
3.
.....= xy+1-3xy / y=1-2xy / y
4.
...= 6*2/3 *x^(2+1)*y^(1-2)= 4x³/ y
5.
(5*5^-7)(4*10^4)=5^-6 *4*2^4 *5^4= 5^-2 * 2^6 = 2^6 / 25=64/25=2,56 >0.015
6.
0,01x+0,1x- 0,5=0,05
0,11x= 0,55
x=5
8.
....= (b-c)²-c²+2b² /b(b-c) = (b-c -c)(b-c+c) + 2b² / b(b-c) = b(b-2c) +2b² / b(b-c) = b-2c-2b / b-c = 3b-2c / b-c
9.
...= 5^n / 5^(n-2) - 5^(n-1) / 5^(n-2) = 5² - 5 =25-5 =20