Question

化简下列分式①m² - 2m/4-m² ②x²+4x+4/4+2x ③ 12a³

Answer 1

m² - 2m/4-m² ＝m(m-2)/(2+m)(2-m)=m/2+m

x²+4x+4/4+2x =(x+2)²/2(2+x)=(x+2)/2

12a³(y-x)²/27(x-y)=12a³(x-y)²/27(x-y)=4a³(x-y)/9

2.分式为0,则分子必为0.（x-2)²>=0,绝对值y+4绝对值>＝0

所以x-2=0且y+4=0

x=2,y=-4

2x+y=0