3/m+5/n=(3n+5m)/mn;
4/x-3/xy=(4y-3)/xy;
7/9ab-13/12ab=7/(3·3·ab)-13/(3·4·ab)=(7·4-13·3)/36ab=(28-39)/36ab=-11/36ab;
Y=cos3x
y`=(cos3x)`*(3x)`=-sin3x *3=-3sin3x
3m-2n=9
<span>5m+n=15 |*2
3m-2n=9
10m+2n=30
13m= 39
m= 3
n= 0
Ответ: (3;0)</span>
1)=(x-y)(a-b);
2)=(a+b)(3x-4y);
3)=3x(m-2n)-4y(m-2n)=(3x-4y);
4)=3a(x-y)-(x-y)=(3a-1)(x-y);
5)=(y-3)(y-3)-4(y-3)= (y-3)(y-3-4)=(y-3)(y-7);
6)= (x+2)(3y-1+2y-7)=(x+2)(5y-8)