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Răspunsuri la întrebare
a) 7 × 8 + 2 × 7 + 9 × 10 = 160
= 7 × ( 8 + 2 ) + 9 × 10 =
= 7 × 10 + 9 × 10 =
= 10 × ( 7 + 9 ) =
= 10 × 16 =
= 160
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b) 37 × 28 + 42 × 37 - 42 × 15 =
= 37 × ( 28 + 42 ) - 42 × 15 =
= 37 × 70 - 42 × 15 =
= 2 590 - 630 =
= 1 960
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c) 207 × 28 + 207 × 180 - 208 × 206 = 208
= 207 × ( 28 + 180 ) - 208 × 206 =
= 207 × 208 - 208 × 206 =
= 208 × ( 207 - 206 ) =
= 208 × 1 =
= 208
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d)
3009 × 3008 - 3008 × 3007 - 2 × 3006 = 2
= 3008 × ( 3009 - 3007 ) - 2 × 3006 =
= 3008 × 2 - 2 × 3006 =
= 2 × ( 3008 - 3006 ) =
= 2 × 2 =
= 4
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e)
5010 × 5009 + 5009 - 5011 × 5008 = 5011
= 5009 × ( 5010 + 1 ) - 5011 × 5008 =
= 5009 × 5011 - 5011 × 5008 =
= 5011 × ( 5009 - 5008 ) =
= 5011 × 1 =
= 5011
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f)
2016 × 2015 + 2 × 2016 - 2017 × 2015 = 2017
= 2016 × ( 2015 + 2 ) - 2017 × 2015 =
= 2016 × 2017 - 2017 × 2015 =
= 2017 × ( 2016 - 2015 ) =
= 2017 × 1 =
= 2017