Question

P/u care valori ale variabilei valoarea raportului algebric este numar intreg:
a)$\frac{7}{x-2}$
b)$\frac{-5}{3-x}$
c)$\frac{9}{2+x}$

Answer 1

a)x-2∈D7
D7={1,7}
x-2=1⇒x=1+2⇒x=3
x-2=7⇒x=7+2⇒x=9
x∈{3,9}

b)3-x∈D{-5}
d{-5}={-1,-5}
3-x=-1⇒-x=-1-3⇒-x=-4  inmultim cu -1⇒x=4
3-x=-5⇒-x=-5+-3⇒-x=-8 inmultim cu -1⇒x=8
x∈{4,8}

c)2+x∈D9
D9={1,3,9}
2+x=1⇒x=1-2⇒x=-1
2+x=3⇒x=3-2⇒x=1
2+x=9⇒x=9-2⇒x=7
x∈{-1,1,7}