Explicație pas cu pas:
a) 26 × 2 = 13 × 4
26 × 2 = 52
13 × 4 = 52
26 × 2 = 13 × 4 (adevărat)
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b) 87 × 4 = 58 × 64
87 × 4 = 348
58 × 64 = 3712
87 × 4 = 58 × 64 (fals)
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c) 58 × 5 = 7 × 41
58 × 5 = 290
7 × 41 = 287
58 × 5 = 7 × 41 (fals)
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d) 25 × 4 = 3 × 35
25 × 4 = 100
3 × 35 = 105
25 × 4 = 3 × 35 (fals)