Question

已知m+n=12 ,mn=3,那么m^2-mn+n^2=?

Answer 1

(m+n)^2=m^2+2mn+n^2

m^2-mn+n^2

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

=(m+n)^2-3mn

=144-9

=135

楼主没错啊……