Question

3道简单填空题1、x平方+y平方=(x+y)平方-（ ）=（x-y）平方+（ ）2、m平方+1/m平方=（m+1/m）平

Answer 1

1.2xy 2xy 2.2 3.29

1.x^2+y^2

=x^2+2xy+y^2-2xy

=(x+y)^2-2xy

x^2+y^2

=x^2-2xy+y^2+2xy

=(x-y)^2+2xy

2.m^2+(1/m)^2

=m^2+2+(1/m)^2-2

=(m + 1/m)^2-2

3.x^2+y^2

=(x-y)^2+2xy

=3^2+2*10

=29