Question

a) aflati numerele naturale x pentru care 9/x+3 este fractia supraunitara                                     b) aflati numarul natural x pentru care are loc relatia 37/18--5/18=x--21/18

Answer 1

x+3∈D9
D9={1,3,9}
x+3=1⇒x=1-3⇒x=-2
x+3=3⇒x=0
x+3=9⇒x=9-3⇒x=6
x∈{-2,0,6}
daca x=-2 fractia devine 9/(-2+3)=9/1=9
daca x=0⇒9/(0+3)=9/3=3
x=6⇒9/(6+3)=9/9=1

b)37/18-5/18=x-21/18
sau x-21/18=37/18-5/18
x-21/18=32/18
x=32/18+21/18
x=53/18