Question

Gasiti numerele naturale x si y astfel incat

a) x+y=4
b) x - y + 4; x ≤ 10 si y > 5
c) x - y =3; x ≤ 13 si y > 7
d) x + 7 ≤ 10
e) x - 3 > 11 si x este cifra
f) x - 15 > 78 si x este numar de 2 cifre

Answer 1

a) x = 0
     y = 4

x = 1
y = 3

x = 2
y = 2

x = 3
y = 1

x = 4
y = 0

b) x = y - 4 ≤ 10
y ≤ 10 + 4
y≤ 14
si stim ca y > 5 si y∈N, deci y ∈ {6, 7, 8, 9, 10, 11, 12, 13, 14}
pentru y = 6, x = 2
y = 7, x = 3
y = 8, x = 4
y = 9, x = 5
y = 10, x = 6
y = 11, x = 7
y = 12, x = 8
y = 13, x = 9
x∈{3,4,5,6,7,8,9}

c) x - y = 3
x = y + 3 ≤ 13
y ≤ 10
dar y > 7
deci y ∈ {8, 9, 10}
Pentru y = 8, x = 11
y = 9, x = 12
y = 10, x = 13
x ∈{11, 12, 13}

d) x + 7 ≤ 10
x ≤ 3
x ∈{0, 1, 2, 3}

e) x > 14 si este cifra ????
x ∈{15, 16, 17, ....?? nu am inteles conditia..

f) x > 78 + 15 = 93
si x < 100
x∈{94, 95, 96, 97, 98, 99}