初一计算题(请写清楚步骤）1.（x+5)(x+5)-(x-2)(x-3)2.（2x-y)(2x-y)-4(x-y)(x+2y)3.（x+y+z)(x-y+z)
问题描述：
初一计算题(请写清楚步骤）
1.（x+5)(x+5)-(x-2)(x-3)
2.（2x-y)(2x-y)-4(x-y)(x+2y)
3.（x+y+z)(x-y+z)
答
1.（x+5)(x+5)-(x-2)(x-3)
=x^2+10x+25-(x^2-5x+6)
=x^2+10x+25-x^2+5x+6
=15x+31
2.（2x-y)(2x-y)-4(x-y)(x+2y)
=4x^2-4xy+y^2-4(x^2+xy-2y^2)
=4x^2-4xy+y^2-4x^2-4xy+8y^2
=9y^2-8xy
3.（x+y+z)(x-y+z)
=[(x+z)+y][(x+z)-y]
=(x+z)^2-y^2
=x^2+2xz+z^2-y^2
答
1.（x+5)(x+5)-(x-2)(x-3)=x^2+10x+25-(x^2-5x+6)=x^2+10x+25-x^2+5x+6=15x+312.（2x-y)(2x-y)-4(x-y)(x+2y)=4x^2-4xy+y^2-4(x^2+xy-2y^2)=4x^2-4xy+y^2-4x^2-4xy+8y^2=9y^2-8xy3.（x+y+z)(x-y+z)=[(x+z)+y][(x+z)-y...