Question

Determinati nr natural xy stiind ca xy+yx=99 si y-x=5

Answer 1

10x+y+10y+x=99
11x+11y=99
x+y=99:11=9
Y-x=5
x+y=9
Daca adunam cele doua ecuatii
2y=14 , y=7
7-x=5
x=2
Numarul este, 27

Answer 2

XY+YX= 99
Scriem ecuatia in baza 10
10X+Y +10Y+X = 99
11X+11Y = 99
11(X+Y) = 99
X+Y = 99:11
X+Y = 9
Y-X= 5
_______( + )
2Y = 14
Y = 14:2
Y = 7
X = 9-7
X = 2

XY = 27