Răspunsuri

2014-10-20T09:45:18+03:00
4a+7=26
4a=26-7
4a=21
a=21/4
fals
4a+7=38
4a=38-7
4a=31
a=31/4
fals
4a+7=43
4a=43-7
4a=36
a=36/4
a=9
deci 4a+7∈ {43}