Question

若-2x的2次方y（-x的m次方y-3xy的3次方）等于2x5次方y的2次方-6x的3次方y的n次方，求mn

Answer 1

即2x(2+m)y^2+6x^3y^4=2x^5y^2-6x^3y^n
所以2+m=5,4=n
则m=3,n=4

Answer 2

x^1/2-x^-(1/2)=5
平方
x-2+1/x=25
x+1/x=27
平方
x^2+2+1/x^2=729
x^2+1/x^2=727
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