一道计算题.谢

网友回答

原式=2/(1×2)+2/(2×3)+2/(3×4)+…+2/(10×11)
=2×(1-1/2)+2×(1/2-1/3)+2×(1/3-1/4)+…+2×(1/10-1/11)
=2×(1-1/2+1/2-1/3+1/3-1/4+…+1/10-1/11)
=2×(1-1/11)
=2×10/11
=20/11
======以下答案可供参考======
供参考答案1:
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