1.-25x^2-30xy-9y^2
=-(25x²+30xy+9y²)
=-(5x+3y)²
2.34^2+34*32+16^2
=34²+2*34*16+16²
=(34+16)²
=50²
=2500
3.38.9^2-2*38.9*48.9+48.9^2
=(38.9-48.9)²
=(-10)²
=100
4.54.5^2-30*16.35+4.5^2
=这个题目好像是错的
1.-25x^2-30xy-9y^2
=-(25x²+30xy+9y²)
=-(5x+3y)²
2.34^2+34*32+16^2
=34²+2*34*16+16²
=(34+16)²
=50²
=2500
3.38.9^2-2*38.9*48.9+48.9^2
=(38.9-48.9)²
=(-10)²
=100
4.54.5^2-30*16.35+4.5^2
=这个题目好像是错的