先化简再求值(2a+b)(2a-b)+3(2a-b)^2+(-3a)(4a-3b)其中a=-1,b=-2
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![先化简再求值(2a+b)(2a-b)+3(2a-b)^2+(-3a)(4a-3b)其中a=-1,b=-2](/uploads/image/z/211542-6-2.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%282a%2Bb%29%282a-b%29%2B3%282a-b%29%5E2%2B%28-3a%29%284a-3b%29%E5%85%B6%E4%B8%ADa%3D-1%2Cb%3D-2)
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先化简再求值(2a+b)(2a-b)+3(2a-b)^2+(-3a)(4a-3b)其中a=-1,b=-2
先化简再求值(2a+b)(2a-b)+3(2a-b)^2+(-3a)(4a-3b)其中a=-1,b=-2
先化简再求值(2a+b)(2a-b)+3(2a-b)^2+(-3a)(4a-3b)其中a=-1,b=-2
=4a^2-b^2+3(4a^2-4ab+b^2)-12a^2+9ab
=4a^2-b^2+12a^2-12ab+3b^2-12a^2+9ab
=4a^2+2b^2-3ab
=4+8-6
=6
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