Question

设m＞n＞0,m平方+n平方=3mn,则mn分之m平方-n平方

Answer 1

答案应选择B

设m＞n＞0,m平方+n平方=3mn,

m^2-2mn+n^2=mn

(m-n)^2=mn

m-n=√mn

m^2+n^2=3mn

m^2+2mn+n^2=3mn+2mn

(m+n)^2=5mn

m+n=√5mn

m^2-n^2

=(m+n)(m-n)

=√5mn *√mn

(m^2-n^2)/mn=√5