Question

Aflați nr necunoscut (Cl a iv)

[(3×r+5)x3+5]×3+5=92

[18+480:(44×a-2806)]×18-100×11=88

[1545:(201-2×n)+95]×3-18=312

3+3×[3+3×(3-3:a)]=510:17

[48000:(5×c+260)-18]+45=1875÷25

15:[74-(1263-9×9:a:3):84-14×4]×30=150​

Answer 1

Răspuns:

Explicație pas cu pas:

[ ( 3 × r + 5 ) × 3 + 5 ] × 3 + 5 = 92

[ ( 3 × r + 5 ) × 3 + 5 ] × 3 = 92 - 5

( 3 × r + 5 ) × 3 + 5 = 87 : 3

( 3 × r + 5 ) × 3 + 5 = 29

( 3 × r + 5 ) × 3 = 29 - 5

( 3 × r + 5 ) × 3 = 24

3 × r + 5 = 24 : 3

3 × r + 5 = 8

3 × r = 8 - 5

3 × r = 3

r = 3 : 3

r = 1  → numarul aflat prin metoda mersului invers

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[ 18 + 480 : ( 44 × a - 2 806 ) ] × 18 - 100 × 11 = 88

[ 18 + 480 : ( 44 × a - 2 806 ) ] × 18 - 1100 = 88

 [ 18 + 480 : ( 44 × a - 2 806 ) ] × 18 = 88 + 1 100

18 + 480 : ( 44 × a - 2 806 ) = 1 188 : 18

18 + 480 : ( 44 × a - 2 806 ) = 66

480 : ( 44 × a - 2 806 ) = 66 - 18

480 : ( 44 × a - 2 806 ) = 48

44 × a - 2 806 = 480 : 48

44 × a - 2 806 = 10

44 × a = 10 + 2 806

44 × a = 2 816

a = 2 816 : 44

a = 64

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[ 1 545 : (201 - 2 × n ) + 95 ] × 3 - 18 = 312

[ 1 545 : (201 - 2 × n ) + 95 ] × 3 = 312 + 18

[ 1 545 : (201 - 2 × n ) + 95 ] × 3 = 330

1 545 : (201 - 2 × n ) + 95 = 330 : 3

1 545 : (201 - 2 × n ) + 95 = 110

1 545 : (201 - 2 × n ) = 110 - 95

1 545 : (201 - 2 × n ) = 15

201 - 2 × n = 1 545 : 15

201 - 2 × n = 103

2 × n = 201 - 103

2 × n = 98

n = 98 : 2

n = 49

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3 + 3 × [ 3 + 3 × ( 3 - 3 : a ) ] = 510 : 17

3 + 3 × [ 3 + 3 × ( 3 - 3 : a ) ] = 30

3 × [ 3 + 3 × ( 3 - 3 : a ) ] = 30 - 3

3 × [ 3 + 3 × ( 3 - 3 : a ) ] = 27

3 + 3 × ( 3 - 3 : a ) = 27 : 3

3 + 3 × ( 3 - 3 : a ) = 9

3 × ( 3 - 3 : a ) = 9 - 3

3 × ( 3 - 3 : a ) = 6

3 - 3 : a = 6 : 3

3 - 3 : a = 2

3 : a = 3 - 2

3 : a = 1

a = 3 : 1

a = 3

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[ 48 000 : ( 5 × c + 260 ) - 18 ] + 45 = 1 875 : 25

[ 48 000 : ( 5 × c + 260 ) - 18 ] + 45 = 75

48 000 : ( 5 × c + 260 ) - 18 = 75 - 45

48 000 : ( 5 × c + 260 ) - 18 = 30

48 000 : ( 5 × c + 260 ) = 30 + 18

48 000 : ( 5 × c + 260 ) = 48

5 × c + 260 = 48 000 : 48

5 × c + 260 = 1 000

5 × c = 1 000 - 260

5 × c = 740

c = 740 : 5

c = 148

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15 : [ 74 - ( 1 263 - 9 × 9 : a : 3 ) : 84 - 14 × 4 ] × 30 = 150

15 : [ 74 - ( 1 263 - 81 : a : 3 ) : 84 - 56 ] = 150 : 30

15 : [ 74 - ( 1 263 - 81 : a : 3 ) : 84 - 56 ] = 5

74 - ( 1 263 - 81 : a : 3 ) : 84 - 56 = 15 : 5

74 - ( 1 263 - 81 : a : 3 ) : 84 - 56 = 3

74 - ( 1 263 - 81 : a : 3 ) : 84 = 3 + 56

74 - ( 1 263 - 81 : a : 3 ) : 84 = 59

( 1 263 - 81 : a : 3 ) : 84 = 74 - 59

( 1 263 - 81 : a : 3 ) : 84 = 15

1 263 - 81 : a : 3 = 15 × 84

1 263 - 81 : a : 3 = 1 260

81 : a : 3 = 1 263 - 1 260

81 : a : 3 = 3

81 : a = 3 × 3

81 : a = 9

a = 81 : 9

a = 9

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