Question

12 + [ 32 : 8 + 2 x ( 3 x 5 – a ) – 12 : 2 ] : 2 = 15

Answer 1

Te salut, Seby!

Răspuns:   a = 11

Explicație pas cu pas:

12 + [ 32 : 8 + 2 x ( 3 x 5 – a ) – 12 : 2 ] : 2 = 15

[ 4 + 2 x ( 15 – a ) – 6 ] : 2 = 15 - 12

[ 4 + 2 x ( 15 – a ) – 6 ] : 2 = 3

4 + 2 x ( 15 – a ) – 6 = 3 × 2

4 + 2 x ( 15 – a ) – 6 = 6

4 + 2 x ( 15 – a ) = 6 + 6

4 + 2 x ( 15 – a ) = 12

2 x ( 15 – a ) = 12 - 4

2 x ( 15 – a ) = 8

15 – a = 8 : 2

15 – a = 4

a = 15 - 4

a = 11 → numărul, aflat prin metoda mersului invers

Verific:

12 + [ 32 : 8 + 2 x ( 3 x 5 – 11 ) – 12 : 2 ] : 2 = 15

= 12 + ( 4 + 2 × 4 - 6 ) : 2 =

= 12 + 6 : 2 =

= 12 + 3 =

= 15