Răspuns :

 

1)

9 × 1 + 1 = 9 + 1 = 10

9 × 2 + 1 = 18 + 1 = 19

9 × 3 + 1 = 27 + 1 = 28

9 × 4 + 1 = 36 + 1 = 37

9 × 5 + 1 = 45 + 1 = 46

9 × 6 + 1 = 54 + 1 = 55

9 × 7 + 1 = 63 + 1 = 64

9 × 8 + 1 = 72 + 1 = 73

9 × 9 + 1 = 81 + 1 = 82

9 × 10 + 1 = 90 + 1 = 91

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ab  ∈  {10; 19; 28; 37; 46; 55; 64; 73; 82; 91}

2)

5 + 5 : {[5 + 5 × (a - 5)] : 5 - 5} = 10

5 : {[5 + 5 × (a - 5)] : 5 - 5} = 10 - 5

5 : {[5 + 5 × (a - 5)] : 5 - 5} = 5

{[5 + 5 × (a - 5)] : 5 - 5} = 5 : 5

[5 + 5 × (a - 5)] : 5 - 5 = 1

[5 + 5 × (a - 5)] : 5 = 1 + 5

[5 + 5 × (a - 5)] : 5 = 6

[5 + 5 × (a - 5)] = 6 × 5

5 + 5 × (a - 5) = 30

5 × (a - 5) = 30 - 5

5 × (a - 5) = 25

(a - 5) = 25 : 5

a - 5 = 5

a = 5 + 5

a = 10

 

Răspuns:

1)

ab:9= x, r=1

ab=9×2+1=19

ab=9×3+1=28

ab=9×4+1=37

ab=9×5+1=46

ab=9×6+1=55

ab=9×7+1=64

ab=9×8+1=73

ab=9×9+1=82

ab=9×10+1=91

Nr de forma ab sunt: 19,28,37,46,55,64,73,82,91

2)

5+5:{[5+5x(a-5)]:5-5}=10

5:{[5+5x(a-5)]:5-5}=5

[5+5x(a-5)]:5-5=25

[5+5x(a-5)]:5=30

5+5x(a-5)=150

5x(a-5)=145

a-5=145/5x

a=145/5x+5

a=29/x+5

Amflicam 5 cu 1/x

a=(29+5)/x

a=34/x

Explicație pas cu pas:

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