【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3

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【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3【(2x+3)(2x-3)-7x

【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3
【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3

【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)其中x=3
【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)
=【4X^2-9-7x^2+21X+4X^2-12X+9】÷(-2x)
=(X^2+9X)÷(-2x)
=(X+9)/-2
=(3+9)/-2
=-6

原式=x^2+9x=9+27=36

原式=(4x²-9-7x²+21x+4x²-12x+9)÷(-2x)
=(x²+9x)÷(-2x)
=-(x+9)/2
=-(3+9)/2
=-6

因为x=3，所以原式可化为如图所示：

还望采纳，谢谢~

【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)
=[(2x+3)(2x-3)+(2x-3)^2-7x(x-3)]÷(-2x)
={(2x-3)[(2x+3)+(2x-3)]-7x(x-3)}÷(-2x)
=[4x(2x-3)-7x(x-3)]÷(-2x)
=[4(2x-3)-7(x-3)]÷(-2)
=[8x-12-7x+21]÷...

全部展开

【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)
=[(2x+3)(2x-3)+(2x-3)^2-7x(x-3)]÷(-2x)
={(2x-3)[(2x+3)+(2x-3)]-7x(x-3)}÷(-2x)
=[4x(2x-3)-7x(x-3)]÷(-2x)
=[4(2x-3)-7(x-3)]÷(-2)
=[8x-12-7x+21]÷(-2)
=(x+9)÷(-2)
代入x=3得：
【(2x+3)(2x-3)-7x(x-3)+(2x-3)^2】÷(-2x)
=(3+9)÷(-2)
=-6
希望对你有帮助，望君采纳，谢谢~

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