1.数学计算题 2.先化简,再求值.1.(x+2)(x²+4)(x-2) 2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2.
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![1.数学计算题 2.先化简,再求值.1.(x+2)(x²+4)(x-2) 2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2.](/uploads/image/z/574010-26-0.jpg?t=1.%E6%95%B0%E5%AD%A6%E8%AE%A1%E7%AE%97%E9%A2%98+2.%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC.1.%EF%BC%88x%2B2%EF%BC%89%28x%26%23178%3B%2B4%29%EF%BC%88x-2%EF%BC%89+++++++++++++++2.%EF%BC%88x%26%23178%3By%26%23178%3B-4%EF%BC%89%EF%BC%88-x%26%23178%3By%26%23178%3B-4%EF%BC%89-4%EF%BC%88xy-1%2F2%EF%BC%89%E4%B9%98%EF%BC%88xy-1%2F2%EF%BC%89%2C%E5%85%B6%E4%B8%ADx%3D1%2Cy%3D-2.)
1.数学计算题 2.先化简,再求值.1.(x+2)(x²+4)(x-2) 2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2.
1.数学计算题 2.先化简,再求值.
1.(x+2)(x²+4)(x-2) 2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2.
1.数学计算题 2.先化简,再求值.1.(x+2)(x²+4)(x-2) 2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2.
(x+2)(x²+4)(x-2)
=(x+2)(x-2) (x²+4)
=(x²-4)(x²+4)
=x⁴-16
2.(x²y²-4)(-x²y²-4)-4(xy-1/2)乘(xy-1/2),其中x=1,y=-2
(x²y²-4)(-x²y²-4)-4(xy-1/2)·(xy-1\2),
=-[(xy)²-4²]-4(xy-1/2)²
=-[(-2)²-4²]-4(-2-1/2)²
=-(4-16)-4*(5/2)²
=12-4*25/4
=12-25
=-13
第一题用两次平方差,x的四次方减十六;第二题的第二个括号先提取负号,和第一个括号进行平方差,接着就是用完全平方啦,孩纸,慢慢算吧
﹙X-2﹚﹙X+2﹚﹙X²-4﹚=﹙X²-4﹚﹙X²+4﹚=X⁴-16 ﹣﹙X²Y²-4﹚﹙X²Y²+4﹚-4﹙XY-1/2﹚²=16-X⁴Y⁴-4﹙X²Y²-XY+1/4﹚=16-8-4﹙4+2+1/4﹚=﹣17