Помогите срочно надо

1
а) $28b^6/c^3 * c^5/84b^6=c^2/3$
б) $30x^2y*z/72xy=5xz/12$
в) $3(x+2)/(x+3)*(x-3)(x+3)/(x-2)(x+2)=3(x-3)/(x-2)$
г) $(2a-b)/a*(ab+2a-ab)/b(2a-b)=(2a-b)/a*2a/b(2a-b)=2/b$
2
y=4/[ гипербола в 1 и 3ч
х -4 -2 -1 1 2 4
D(y)∈(-∞;0) U (0;4)
y>0
x∈(0;∞)
3
1)2/(3-y)²+1/(3-y)(3+y)=(6+2y+3-y)/(3-y)²(3+y)=(y+9)/(3-y)²(3+y)
2)(y-3)²*(y+9)/(3-y)²(3+y)=(y+9)/(3+y)
3)2y/(y+3)+(y+9)/(3+y)=(3y+9)/(y+3)=3(y+3)/(y+3)=3
4
{1-6/(10-5x)≠0⇒1≠6/(10-5x)⇒10-5x≠6⇒5x≠4⇒x≠0,8
{10-5x≠0⇒5x≠10⇒x≠2
x∈(-∞;0,8) U (0,8;2) U (2;∞)