已知A=x^2-5x,B=x^2-10x+3,求2A-B的值

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已知A=x^2-5x,B=x^2-10x+3,求2A-B的值已知A=x^2-5x,B=x^2-10x+3,求2A-B的值已知A=x^2-5x,B=x^2-10x+3,求2A-B的值2A-B=2(x&#

已知A=x^2-5x,B=x^2-10x+3,求2A-B的值
已知A=x^2-5x,B=x^2-10x+3,求2A-B的值

已知A=x^2-5x,B=x^2-10x+3,求2A-B的值
2A-B
=2(x²-5x)-(x²-10x+3)
=2x²-10x-x²+10x-3
=x²-3

=2x^2-10x-x^2+10x-3
=x^2-3

2A-B=x^2-3

A=x^2-5x,
2A=2x^2-10x
B=x^2-10x+3
2A-B=2x^2-10x-﹙x^2-10x+3﹚
=x^2-3