已知x=1999,则|4x²-5x+9|-4|x²+2x+2|+3x+7=
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![已知x=1999,则|4x²-5x+9|-4|x²+2x+2|+3x+7=](/uploads/image/z/468482-50-2.jpg?t=%E5%B7%B2%E7%9F%A5x%3D1999%2C%E5%88%99%7C4x%26%23178%3B-5x%2B9%7C-4%7Cx%26%23178%3B%2B2x%2B2%7C%2B3x%2B7%3D)
已知x=1999,则|4x²-5x+9|-4|x²+2x+2|+3x+7=
已知x=1999,则|4x²-5x+9|-4|x²+2x+2|+3x+7=
已知x=1999,则|4x²-5x+9|-4|x²+2x+2|+3x+7=
|4x²-5x+9|-4|x²+2x+2|+3x+7 4x²-5x+9=4(x²-5x/4)+9=4(x-5/8)²+9-25/16>0可以直接去绝对值
=4x²-5x+9-4x²-8x-8+3x+7 x²+2x+2=(x+1)²+1>0可以直接去绝对值
=4x²-4x²-5x-8x+3x+9-8+7
=-10x+8
当x=1999
-10x+8
=-19990+8
=-19982
-19982