Răspuns :
|2x-3|=5 este echivaleta cu:
[tex]2x-3=\pm5[/tex]
2x+3=5⇒x=1
2x+3=-5⇒x=-4
Deci x∈{1; -4}
[tex]2x-3=\pm5[/tex]
2x+3=5⇒x=1
2x+3=-5⇒x=-4
Deci x∈{1; -4}
l 2x - 3 l = 5
l 2x - 3 l = 2x - 3 daca 2x - 3 > 0 => x > 3/2
l 2x - 3 l = -(2x - 3) daca 2x - 3 < 0 => x < 3/2
Avem ecuatiile:
1)
2x - 3 = 5
2x = 5 + 3
2x = 8
x = 8 / 2 = 4
2)
-(2x - 3) = 5
-2x + 3 = 5
-2x = 5 - 3
-2x = -2
x = (-2) / (-2) = -1
PROBE:
1)
x = 4
l 2*4 - 3 l =l 8 - 3 l = l 5 l = 5 OK
2)
x = -1
l 2*(-1) - 3 l = l -2 - 3 l = l -5 l = 5 OK
l 2x - 3 l = 2x - 3 daca 2x - 3 > 0 => x > 3/2
l 2x - 3 l = -(2x - 3) daca 2x - 3 < 0 => x < 3/2
Avem ecuatiile:
1)
2x - 3 = 5
2x = 5 + 3
2x = 8
x = 8 / 2 = 4
2)
-(2x - 3) = 5
-2x + 3 = 5
-2x = 5 - 3
-2x = -2
x = (-2) / (-2) = -1
PROBE:
1)
x = 4
l 2*4 - 3 l =l 8 - 3 l = l 5 l = 5 OK
2)
x = -1
l 2*(-1) - 3 l = l -2 - 3 l = l -5 l = 5 OK