Question

12 Puncte + coronita Calculeaza in doua moduri :

108 : 18 + 72 : 18

45 x 60 : 15

99 + 99 : 99 + 100

47 x 53 + 53 x 43 - 90 x 52

(35 x 45) : (7 x 9 )

Answer 1

108 : 18 + 72 : 18 = 6 + 4 = 10 → primul mod

=  ( 108 + 72 ) : 18 = 180 : 18 = 10 → al doilea mod

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45 × 60 : 15 = 2 700 : 15 = 180 → primul mod

= 45 × 60 × 1 / 15 = ( 45 / 15 ) × 60 = 3 × 60 = 180 → al doilea mod

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99 + 99 : 99 + 100 = 99 + 1 + 100 = 200 → primul mod

= ( 100 - 1 ) + 1 + 100 = 200 → al doilea mod

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47 × 53 + 53 × 43 - 90 × 52 = 90

= 2 491 + 2 279 - 4 680 =

= 4 770 - 4 680 =

= 90 → primul mod

47 × 53 + 53 × 43 - 90 × 52 =

= 53 × ( 47 + 43 ) - 90 × 52 =

= 53 × 90 - 90 × 52 =

= 90 × ( 53 - 52 ) =

= 90 × 1 =

= 90 → al doilea mod ( dand factor comun )

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( 35 × 45 ) : ( 7 × 9 ) = 1 575 : 63 = 25 → primul mod

= ( 35 / 7 ) × ( 45 / 9 ) = 5 × 5 = 25 → al doilea mod