1；其較短一邊長(zhǎng)為ycm每個(gè)小長(zhǎng)方形較長(zhǎng)的一邊是（60-3y）cm
2；分別用含x,y的代數(shù)式表示陰影A,B的面積,并計(jì)算陰影A,B的面積差
A=(x-2y)(60-3y)=60x-120y-3xy+6y^2
B=[x-(60-3y)]*3y=(x+3y-60)*3y=3xy+9y^2-180y
A-B
=60x-120y-3xy+6y^2-(3xy+9y^2-180y)
=60x-120y-3xy+6y^2-3xy-9y^2+180y
=60x+60y-6xy-3y^2
3；當(dāng)y=10時(shí),A-B=60x+600-60x-300= 300,是定值,不會(huì)隨著x的變化而變化