作业帮已知x=2013,求(5-2x)²-(2x+5)(2x-5)的值
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已知x=2013,求(5-2x)²-(2x+5)(2x-5)的值
已知x=2013,求(5-2x)²-(2x+5)(2x-5)的值
已知x=2013,求(5-2x)²-(2x+5)(2x-5)的值
=(2x-5)²-(2x+5)(2x-5)
=(2x-5)(2x-5-2x-5)
=(2x-5)(-10)
=-10(2x-5)
=-10×(2×2013-5)
=-40210
解(5-2x)²-(2x+5)(2x-5)
=(2x-5)²-(2x+5)(2x-5)
=(4x^2-20x+25)-(4x^2-25)
=-20x+50
故原式=-20x+50
=-20×2013+50
=-40210