Đáp án:
`B = 2 190/191 × 1 1/195 - 1/191 × 1/195 + 3 × 194/195`
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`-> B = 572/191 × 196/195 - 1/191 × 1/195 + 582/195`
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`-> B = 572/191 × 1/195 × 196 - 1/191 × 1/195 + 582 × 1/195`
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`-> B = 1/195 × [572/191 × 196 - 1/191 + 582]`
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`-> B = 1/195 × [572 × 1/191 × 196 - 1/191 + 582]`
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`-> B = 1/195 × [1/191 × (572 × 196 - 1) + 582]`
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`-> B = 1/195 × [1/191 × 112111 + 582]`
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`-> B = 1/195 × [112111/191 + 582]`
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`-> B = 1/195 × [112111/191 + 111162/191]`
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`-> B = 1/195 × 223273/191`
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`-> B = (1 × 223273)/(195 × 191)`
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`-> B = 223273/37245`
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Vậy `B = 223273/37245`
