f.2 maths(1 question only)

(6x-3y/10x^2+xy-3y^2)*(5x^2+8xy+3y^2)
=[3(2x-y)/(2x-y)(5x+3y)]*(5x+3y)(x+y)
=3(x+y)

2007-01-31 22:06:28 補充：
2 -15 32*3-1*5=110x^2+xy-3y^2=(2x-y)(5x+3y)5 31 15*1+3*1=85x^2+8xy+3y^2=(5x+3y)(x+y)