先化简再求值(a+2b/a+b)+(2b^2/a^2-b^2)其中a=-2,b=1/3
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![先化简再求值(a+2b/a+b)+(2b^2/a^2-b^2)其中a=-2,b=1/3](/uploads/image/z/983587-67-7.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC%28a%2B2b%2Fa%2Bb%29%2B%282b%5E2%2Fa%5E2-b%5E2%29%E5%85%B6%E4%B8%ADa%3D-2%2Cb%3D1%2F3)
先化简再求值(a+2b/a+b)+(2b^2/a^2-b^2)其中a=-2,b=1/3
先化简再求值(a+2b/a+b)+(2b^2/a^2-b^2)其中a=-2,b=1/3
先化简再求值(a+2b/a+b)+(2b^2/a^2-b^2)其中a=-2,b=1/3
原式=(a+2b)/(a+b)+2b²/[(a+b)(a-b)]
=(a+2b)(a-b)/[(a+b)(a-b)]+2b²/[(a+b)(a-b)]
=(a²-ab+2ab-2b²+2b²)/[(a+b)(a-b)]
=a(a+b)/[(a+b)(a-b)]
=a/(a-b)
=-2/(-2-1/3)
=6/7