5
(4-a)/9a-3)-(2a-5)/(a-3)=(4-a-2a+5)/(a-3)=(9-3a)/(a-3)=
=-3(a-3)/(a-3)=-3 ответ 2
6
1)a/b-b/a=(a²-b²)/ab
2)(a-b)(a+b)/ab*3ab/(a+b)=3(a-b)
ответ 4
B1
7x²/(3-x)*(x-3)(x+3)/14x³=-(x+3)/2x
B2
(x+5)²/x(x+5)*x³/(x-5)(x+5)=x²/(x-5)
B3
(c-d)(c+d)/(c-d)²=(c+d)/(c-d)
B4
5y/(y-1)+7y/2(y-1)=(10y+7y)/2(y-1)=17y/2(y-1)
C1
x²-3x+m=x²-5x+xa-5a
x²-3x+m=x²-x(5-a)-5a
5-a=3⇒a=2
m=-5a⇒m=-10
C2
2a-8≠0
2a≠8
a≠4