Question

repede imi trebuie
sper sa stiti

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Answer 1

Răspuns:

Explicație pas cu pas:

1.

28 + 2 × ( 2660 + 76 : x ) : 893 = 34

2 × ( 2660 + 76 : x ) : 893 = 34 - 28

2 × ( 2660 + 76 : x ) : 893 = 6

2 × ( 2660 + 76 : x ) = 6×893

2660 + 76 : x = 5358 : 2

2660 + 76 : x = 2 679

76 : x = 2 679 - 2 660

76 : x = 19

x = 76 : 19

x = 4 → numărul aflat prin metoda mersului invers

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2.

2⁷ : 4³ + 3⁹ x 27⁵ : 3²⁰+ (3¹ x 2⁴ - 4²) : 2³ = 87

= 2⁷ : (2²)³ + 3⁹ x (3³)⁵ : 3²⁰ + (3x16 - 16) : 8 =

= 2⁷ : 2⁽²ˣ³⁾ + 3⁹ x 3⁽³ˣ⁵⁾ : 3²⁰ + (48-16) : 8 =

= 2⁽⁷⁻⁶⁾ + 3⁽⁹⁺¹⁵⁻²⁰⁾ + 32 : 8 =

= 2¹ + 3⁴ + 4 =

= 6+81 =

= 87

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3.

a = (3²¹ + 3²⁰ + 3¹⁸) : 37

a = (3¹⁸x3³ + 3¹⁸x3² + 3¹⁸x1) : 37

a = 3¹⁸ x ( 3³ + 3² + 1) : 37

a = 3⁽⁹ˣ²⁾ x (27+9+1) : 37

a = (3⁹)² x 37 : 37

a = (3⁹)² → pătrat perfect