(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)^2,其中x=1.5,y=3.9,先化简再求值过程详细,请各位大神帮帮忙
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![(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)^2,其中x=1.5,y=3.9,先化简再求值过程详细,请各位大神帮帮忙](/uploads/image/z/11504445-69-5.jpg?t=%28x-1%2F2y-1%29%28x-1%2F2y%2B1%29-%28x-1%2F2y%2B1%29%5E2%2C%E5%85%B6%E4%B8%ADx%3D1.5%2Cy%3D3.9%2C%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%E8%BF%87%E7%A8%8B%E8%AF%A6%E7%BB%86%2C%E8%AF%B7%E5%90%84%E4%BD%8D%E5%A4%A7%E7%A5%9E%E5%B8%AE%E5%B8%AE%E5%BF%99)
(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)^2,其中x=1.5,y=3.9,先化简再求值过程详细,请各位大神帮帮忙
(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)^2,其中x=1.5,y=3.9,先化简再求值
过程详细,请各位大神帮帮忙
(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)^2,其中x=1.5,y=3.9,先化简再求值过程详细,请各位大神帮帮忙
(x-1/2y-1)(x-1/2y+1)-(x-1/2y+1)²
=(x-1/2y)²-1²-(x-1/2y+1)²
=(X-1/2y)²-1-[(x-1/2y)²+2(x-1/2y)+1]
=(X-1/2y)²-1-(x-1/2y)²-2(x-1/2y)-1
=-2-2(x-1/2y)
=-2-2x+y
把数值代入得:
原式=-2-2*(1.5)+3.9
=-2-3+3.9
=-2+0.9
=-1.1
1.2乘8.52
原式=[(x-1/2y)-1][(x-1/2y)+1]-[(x-1/2y)+1]²
=(x-1/2y)²-1²-(x-1/2y)²-2(x-1/2y)-1
=2(x-1/2y)-2
=2x-y-2
=2*1.5-3.9-2
=-2.9(x-1/2y)²-2(x-1/2y)-1,这个不可以这样拆吧,貌似不对的感...
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原式=[(x-1/2y)-1][(x-1/2y)+1]-[(x-1/2y)+1]²
=(x-1/2y)²-1²-(x-1/2y)²-2(x-1/2y)-1
=2(x-1/2y)-2
=2x-y-2
=2*1.5-3.9-2
=-2.9
收起
提取公因式(x-y/2+1)[(x-y/2-1)-(x-y/2+1)]=-2(x-y/2+1)=-2(1.5-3.9/2+1)=-5+3.9=-1.1