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先化简再求值2(x+4)^2-(X+5)^2-(x+3)(x-3) x=-2
人气:149 ℃ 时间:2020-02-06 09:49:53
解答
原式=2(x²+8x+16)-(x²+10x+25)-(x²-9)
=2x²+16x+32-x²-10x-25-x²+9
=6x+16
=6*(-2)+16
=4
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