Question

1.Rezolvati in Z ecuatiile :
a) |x| = 7
b) |x| = 23
c) |x| = 0
d) |5x-3| = 2
e) |x| = -4
f) |4x| = 16
g) |x+5| = 7

2. Determinati numerele intregi x si y pentru care:
a) xy = -6
b) (2x+1) y = 21
c) (x-4) (y+3) = 35

Answer 1

a)lxl=7 ⇒x∈{-7;7}
b)lxl=23⇒x∈{-23;23}
c)lxl=0⇒x=0
d)l5x-3l=2
5x-3=2 ⇒x=1
5x-3=-2⇒x=$\frac{1}{5}$ ( FALS) deci x=1 singura varianta
e)lxl=-4 -ecuatia nu are solutie
f)l4xl=16
4x=16⇒x=4
4x=-16⇒x=-4 deci x∈{-4;4}
g)lx+5l=7
x+5=7⇒x=2
x+5=-7⇒x=-12 deci x∈{2;-12}