六年级奥数题 简便计算
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六年级奥数题 简便计算
139×137/138+137×139/138
139×137/138+137×139/138
![六年级奥数题 简便计算](/uploads/image/z/2908623-39-3.jpg?t=%E5%85%AD%E5%B9%B4%E7%BA%A7%E5%A5%A5%E6%95%B0%E9%A2%98+%E7%AE%80%E4%BE%BF%E8%AE%A1%E7%AE%97)
139×137/138+137×139/138
=(138+1)×137/138+(138-1)×139/138
=137+137/138+139-139/138
=275+136/138
=275+68/69
=(138+1)×137/138+(138-1)×139/138
=137+137/138+139-139/138
=275+136/138
=275+68/69