Question

cum se rezolva exercitiul: 5+[32-(10:a×4+12)]×7=89

Answer 1

Răspuns:   a = 5

Explicație pas cu pas:

5 + [ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 89

[ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 89 - 5

[ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 84

32 - ( 10 : a × 4 + 12 ) = 84 : 7

32 - ( 10 : a × 4 + 12 ) = 12

10 : a × 4 + 12 = 32 - 12

10 : a × 4 + 12 = 20

10 : a × 4 = 20 - 12

10 : a × 4 = 8

10 : a = 8 : 4

10 : a = 2

a = 10 : 2

a = 5  → numarul, aflat prin metoda mersului invers

Answer 2

5 + [ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 89

[ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 89 - 5

[ 32 - ( 10 : a × 4 + 12 ) ] × 7 = 84

32 - ( 10 : a × 4 + 12 ) = 84 : 7

32 - ( 10 : a × 4 + 12 ) = 12

10 : a × 4 + 12 = 32 - 12

10 : a × 4 + 12 = 20

10 : a × 4 = 20 - 12

10 : a × 4 = 8

10 : a = 8 : 4

10 : a = 2

a = 10 : 2

a = 5