已知:A=5a二次方+2ab,且B=2a二次方-ab-1.(1):计算A-2B; (2):若│a+1│+(b-2)的2次方=0,求A-2B的值
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![已知:A=5a二次方+2ab,且B=2a二次方-ab-1.(1):计算A-2B; (2):若│a+1│+(b-2)的2次方=0,求A-2B的值](/uploads/image/z/5181227-35-7.jpg?t=%E5%B7%B2%E7%9F%A5%3AA%3D5a%E4%BA%8C%E6%AC%A1%E6%96%B9%2B2ab%2C%E4%B8%94B%3D2a%E4%BA%8C%E6%AC%A1%E6%96%B9-ab-1.%281%29%3A%E8%AE%A1%E7%AE%97A-2B%3B+%282%29%3A%E8%8B%A5%E2%94%82a%2B1%E2%94%82%2B%28b-2%29%E7%9A%842%E6%AC%A1%E6%96%B9%3D0%2C%E6%B1%82A-2B%E7%9A%84%E5%80%BC)
已知:A=5a二次方+2ab,且B=2a二次方-ab-1.(1):计算A-2B; (2):若│a+1│+(b-2)的2次方=0,求A-2B的值
已知:A=5a二次方+2ab,且B=2a二次方-ab-1.(1):计算A-2B; (2):若│a+1│+(b-2)的2次方=0,求A-2B的值
已知:A=5a二次方+2ab,且B=2a二次方-ab-1.(1):计算A-2B; (2):若│a+1│+(b-2)的2次方=0,求A-2B的值
A=5a^2+2ab B=2a^2-ab-1
A-2B=5a^2+2ab-2(2a^2-ab-1)=a^2+4ab+2
│a+1│+(b-2)的2次方=0
a+1=0 b-2=0
a=-1 b=2
A-2B=a^2+4ab+2=1-8+2=-5
A+2B=5a2+2ab-2(2a2-ab-1) 所以:A+2B=(-1)2+4(-1x2)+2
=5a2+2ab-4a2+2ab+2 =1-8+2 =5
=a2+4ab+2
因为:Ia+1I+(b-2)2=0
所以:a+1=0 b-2=0
则:a=-1 b=2
A+2B=5a2+2ab-2(2a2-ab-1) A+2B=(-1)2+4(-1x2)+2
=5a2+2ab-4a2+2ab+2 =1-8+2 =5
=a2+4ab+2
Ia+1I+(b-2)2=0
a+1=0 b-2=0
a=-1 b=2