Question

determina numerele naturale de forma xy stiind ca xy+yx=77

Answer 1

XY+YX = 77
10X+Y+10Y+X = 77
11X+11Y = 77
11×(X+Y) = 77
X+Y = 77:11
X+Y = 7
X= 1;2;3;4;5;6
Y= = 6;5;4;3;2;1
XY = 16; 25; 34; 43; 52; 61

Verificare:
16+61 = 77
25+52 = 77
34+43 = 77
43+34 = 77
52+25 = 77
61+16 = 77