（3y）分之2x+（3y）分之5x
=（3y）分之(2x+5x)
=（3y）分之(7x)
（x+y）分之2y-（y+x）分之y-x
=（x+y）分之2y-（x+y）分之(y-x)
=（x+y）分之(2y-y+x)
=（x+y）分之(x+y)
=1
（x²+3x）分之x²+9x+（x²+6x+9）分之x²-9
=x(x+3)分之x(x+9)+(x+3)²分之(x²-9)
=(x+3)²分之(x+3)(x+9)+(x+3)²分之(x²-9)
=(x+3)²分之[(x+3)(x+9)+(x²-9)]
=(x+3)²分之(x²+12x+27+x²-9)
=(x+3)²分之(2x²+12x+18)
=(x+3)²分之2(x+3)²
=2