1.先化简,再求值[(a-1/2)²-(a+1/2)²](a+3),其中a=-2 2.若a+b=5,ab=6,求a^4+b^4,a^8+b^8的值 3.已知a(a-1)-(a²-b)=4,求(a²+b²)/2-ab的值 正确必满意,蟹蟹~
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![1.先化简,再求值[(a-1/2)²-(a+1/2)²](a+3),其中a=-2 2.若a+b=5,ab=6,求a^4+b^4,a^8+b^8的值 3.已知a(a-1)-(a²-b)=4,求(a²+b²)/2-ab的值 正确必满意,蟹蟹~](/uploads/image/z/2738878-70-8.jpg?t=1.%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%5B%EF%BC%88a-1%2F2%EF%BC%89%26%23178%3B-%EF%BC%88a%2B1%2F2%EF%BC%89%26%23178%3B%5D%EF%BC%88a%2B3%EF%BC%89%2C%E5%85%B6%E4%B8%ADa%3D-2+2.%E8%8B%A5a%2Bb%3D5%2Cab%3D6%2C%E6%B1%82a%5E4%2Bb%5E4%2Ca%5E8%2Bb%5E8%E7%9A%84%E5%80%BC+3.%E5%B7%B2%E7%9F%A5a%28a-1%29-%28a%26%23178%3B-b%29%3D4%2C%E6%B1%82%28a%26%23178%3B%2Bb%26%23178%3B%29%2F2-ab%E7%9A%84%E5%80%BC+%E6%AD%A3%E7%A1%AE%E5%BF%85%E6%BB%A1%E6%84%8F%2C%E8%9F%B9%E8%9F%B9%7E)
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1.先化简,再求值[(a-1/2)²-(a+1/2)²](a+3),其中a=-2 2.若a+b=5,ab=6,求a^4+b^4,a^8+b^8的值 3.已知a(a-1)-(a²-b)=4,求(a²+b²)/2-ab的值 正确必满意,蟹蟹~
1.先化简,再求值[(a-1/2)²-(a+1/2)²](a+3),其中a=-2 2.若a+b=5,ab=6,求a^4+b^4,a^8+b^8的值 3.已知a(a-1)-(a²-b)=4,求(a²+b²)/2-ab的值 正确必满意,蟹蟹~
1.先化简,再求值[(a-1/2)²-(a+1/2)²](a+3),其中a=-2 2.若a+b=5,ab=6,求a^4+b^4,a^8+b^8的值 3.已知a(a-1)-(a²-b)=4,求(a²+b²)/2-ab的值 正确必满意,蟹蟹~
[(a-1/2)^2-(a+1/2)^2](a+3)
=[(a-1/2+a+1/2)(a-1/2-a-1/2)](a+3)
=[2ax(-1/4)](a+3)
=-a/2(a+3)
当a=-2
-a/2(a+3)
=-2/2(-2+3)
=-1x1
=-1
[(a-1/2)^2-(a+1/2)^2](a+3)
=[(a-1/2+a+1/2)(a-1/2-a-1/2)](a+3)
=[2ax(-1/4)](a+3)
=-a/2(a+3)
当a=-2
-a/2(a+3)
=-2/2(-2+3)
=-1x1
=-1