Question

Rezolvați în n ecuațile
c) -2x-1=7x+5
d) 2-x=5-2x
e) -3=-x+9
f) x+5=-3x+20

Answer 1

c) -2x-1=7x+5
-2x-7x=5+1
-9x=6
x=-6/9
x nu are solutii in N

d) 2-x=5-2x
-x+2x=5-2
x=3

e) -3=-x+9
-3-9=-x
-12=-x
x=12

f) x+5=-3x+20
x+3x=20-5
4x=15
x=15/4
x nu are solutii in N

Answer 2

c) - 2x - 1 = 7x + 5
- 2x - 7x = 1 + 5
- 9x = 6
x = - 6/9 = - 2/3
x∉N
d) 2 - x = 5 - 2x 
- x + 2x = 5 - 2
x = 3
e) - 3 = - x + 9
- x = - 12
x = 12
f) x + 5 = - 3x + 20
x + 3x = 20 - 5
4x = 15
x = 15/4
x∉N