Question

Aflati pe ,,a" din relatia :
21-4×[1+15:(a-9)]=5
VA ROG REPEDEEEE!
DAU CORONITA !

Answer 1

21-4*[1+15:(a-9)] = 5
4*[1+15:(a-9)] = 21-5
4*[1+15:(a-9)] = 16
1+15:(a-9) = 16:4
1+15:(a-9) =4
15 : (a-9) = 4-1
15 : (a-9) =3
a-9= 15:3
a-9 = 5
a= 5+9
a= 14

Answer 2

$21-4\times\big[1+15:(a-9)\big]=5 \\ \\ -4\times\big[1+15:(a-9)\big] = 5-21\\ \\ -4\times\big[1+15:(a-9)\big] = -16\Big|\times (-1) \\ \\ 4\times\big[1+15:(a-9)\big] = 16\\ \\ 1+15:(a-9) = 16:4 \\ \\ 1+15:(a-9) = 4\\ \\ 15:(a-9) = 4-1 \\ \\ 15:(a-9) = 3 \\ \\ 15 = 3\times(a-9) \\ \\ a-9 = 15:3 \\ \\ a-9 = 5 \\ \\ a = 5+9 \\ \\ a = 14$