Question

Determinați numărul a din: 65:5+6x{21-3x[6x7-72:(a+1)]}=31

Answer 1

Răspuns:

Explicație pas cu pas:

65:5+6x{21-3x[6x7-72:(a+1)]}=31

13 +6x{21-3x[42-72:(a+1)]}=31

6x{21-3x[42-72:(a+1)]}=31 - 13

6x{21-3x[42-72:(a+1)]}= 18

21-3x[42-72:(a+1)] = 18 : 6

21-3x[42-72:(a+1)] = 3

3x[42-72:(a+1)] = 21 - 3

3x[42-72:(a+1)] = 18

42-72:(a+1) = 18 : 3

42-72:(a+1) = 6

72:(a+1) = 42 - 6

72:(a+1) = 36

a + 1 = 72 : 36

a + 1 = 2

a = 2 - 1

a = 1 → numărul căutat, aflat prin metoda mersului invers

Answer 2

Răspuns:

a = 1

Explicație pas cu pas:

65:5+6x{21-3x[6x7-72:(a+1)]} = 31

13 + 6x{21-3x[42-72:(a+1)]} = 31

13 + 6x[21 - 126 + 216:(a+1)] = 31

13 + 6x[-105 + 216:(a+1)] = 31

- 630 + 1296:(a+1) = 31 - 13

1296:(a+1) = 18 + 630

1296:(a+1) = 648

(a+1) = 1296:648

a+ 1 = 2

a = 2-1

a = 1