化简,求值:5a²-(3b²+7ab)+(2b²-5a²),其中a=-0.1,b=0.2

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化简,求值:5a²-(3b²+7ab)+(2b²-5a²),其中a=-0.1,b=0.2
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化简,求值:5a²-(3b²+7ab)+(2b²-5a²),其中a=-0.1,b=0.2
化简,求值:5a²-(3b²+7ab)+(2b²-5a²),其中a=-0.1,b=0.2

化简,求值:5a²-(3b²+7ab)+(2b²-5a²),其中a=-0.1,b=0.2
5a²-(3b²+7ab)+(2b²-5a²)
=5a²-3b²-7ab+2b²-5a²
=-b²-7ab
=-(0.2)²-7*(-0.1)*0.2
=-0.04+0.14
=0.1

5a²-(3b²+7ab)+(2b²-5a²)
=5a²-3b²-7ab+2b²-5²
=-b²-7ab
=-(0.2)²-7×(-0.1)×(0.2)
=-0.04+0.14
=0.1

5a²-(3b²+7ab)+(2b²-5a²)
=5a²-3b²-7ab+2b²-5a²
=7ab-b²
当a=-0.1,b=0.2时
7ab-b²
=7×(-0.1)×0.2-0.2²
=-0.14-0.04
=-0.18