(P+2q)/ (3p-q) - (5q-2p)/(q-3p) =(P+2q)/ (3p-q) + (5q-2p)/(3p-q) =
= (P+2q +5q-2p)/(3p-q) = (7q-p)/(3p-q)
1/x+1/y+1/z+1/t - ?
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___+1/y+1/z+1/t =1/4
1/x+___+1/z+1/t =1/3
1/x+1/y+______ = 1/6
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сложим все три уравнения и разделим на два
1/x+1/y+1/z+1/t =(1/4+1/3+1/6)/2 =(3+4+2)/24 = 1/ (24/9)=1/ (8/3)
ответ за 8/3 часов = 2 часа 40 минут
6-2x<3(x-1) 6-2x<3x-3 5x>9 x>9/5
6-x/2≥x 3x/2≤6 x≤4
Итак 2+3+4=9
ответ А
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