参考・概略です
多いので途中式だけです
(1)
={1(x+2)+1(x-1)}/{(x-1)(x+2)}
={(2x+1)}/{(x-1)(x+2)}
(2)
={1(3x+1)-1(3x)}/{3x(3x+1)}
={1}/{3x(3x+1)}
(3)
={1(x)-1}/{x(x-1)}
={(x-1)}/{x(x-1)}
={1}/{x}
(4)
=[2/(x+1)]+[3/x(x+1)]
={2(x)+3}/{x(x+1)}
={(2x+3)}/{x(x+1)}
(5)
=[x/(x+1)]+[(3x-1)/(x+1)(x-3)]
={x(x-3)+(3x-1)}/{(x+1)(x-3)}
={x²-1}/{(x+1)(x-3)}
={(x+1)(x-1)}/{(x+1)(x-3)}
={(x-1)}/{(x-3)}
(6)
=[{x+4}/{x²-2x}]-[{3}/{x²-3x+2}]
=[{x+4}/{x(x-2)}]-[{3}/{(x-1)(x-2)}]
={(x+4)(x-1)-3(x)}/{x(x-1)(x-2)}
={x²-4}/{x(x-1)(x-2)}
={(x+2)(x-2)}/{x(x-1)(x-2)}
={(x+2)}/{x(x-1)}