1
(x-6)/(x-12)=-2/3
3(x-6)=-2(x-12),x≠6
3x-18=-2x+24
3x+2x=24+18
5x=42
x=42:5
x=8,4
2
30/(x-1)9x+1)-13/(x²+x+1)=(7+18x)/(x-1)(x²+x+1)
x≠1 x≠-1
30(x²+x+1)-13(x²-1)=(x+1)(7+18x)
30x²+30x+30-13x²+13-7x-7-18x²-18x=0
-x²+5x+36=0
x²-5x-36=0
x1+x2=5 U x1*x2=-36
x=-4 U x=9