^是几次方的意思,如5^3=125
圆环面积=πx^2-πy^2=π(x+y)(x-y)=14π
所以(x+y)(x-y)=14
原式=[-6(x+y)^2*(x-y)^3]^2/[3(x+y)(x-y)^2]^2
=36(x+y)^4*(x-y)^6/[9(x+y)^2*(x-y)^4]
=4(x+y)^2*(x-y)^2
=4[(x+y)(x-y)]^2
=196*4
=784