Question

determinati numărul abcd, știind că aaaa-aaa-aa-a=bcbd​

Answer 1

Răspuns:

$\overline{abcd} = \overline{b(b+c)(c+a)(2a+2d)}$

Explicație pas cu pas:

$\overline{aaaa} - \overline{aaa} - \overline{aa} - \overline{a} = \overline{bcbd}\\\\ 1111a - 111a - 11a - a = \overline {bcbd}\\\\ 1000a - 12a = 1000b + 100c + 10b + d\\\\ 988a = 1010b + 100c + d\\\\\overline{abcd} = 1000a + 100b + 10c + d\\\\ 1000a = 1000b + 100c + 10b + d + 12a\\\\\overline{abcd} = 1000b + 100c + 10b + d + 12a + 100b + 10c + d = 1000b + 100(b+c) + 10(c+a) + 1(2a+2d)\\\\\overline{abcd} = \overline{b(b+c)(c+a)(2a+2d)}$.

Cu parantezele mai sus am notat o singura cifra