21 si 22 dau coroana...
Răspunsuri la întrebare
Obs. 1. IxI = a , a > 0
1.1. x= a
1.2 x= -a
ex. IxI = 83 x= 83
x= -83 , S= {+/- 83}
2. IxI = a , a < 0 S = ∅
ex. I x- 8I = -3 , ex. ≠ soluţii, S= ∅
ex.21
a. I-x+ 5I = -10 b. I24- 6xI- 2= -2
S=∅ I24- 6xI = -2+ 2
I24- 6x I = 0
24- 6x = 0
24 = 6xI 6
4 = x S= { 4}
c. I-x+ 1I + (x+ y)² = 0
I-x+ 1I = 0 (x+ y)² = 0
-x+ 1= 0 ( 1+ y)² = 0
-x =-1 (1+ y)( 1+y)= 0
x = 1 1+ y= 0
y= -1
d. -3I2x+ 4I+ 5= -7 , 2x+ 4= a
-3a+ 5= -7
-3a =- 7-5
-3a = -12 I 3
a = 4
2x+ 4 = 4 2x+ 4= -4
2x = 4- 4 2x = -4- 4
2x = 0 2x = -8 I 2
x = 0 x = - 4
S = { -4; 0}
ex. 22
a. I x- 2I- 11= -2Ix- 2I + 4 , I x-2I = a
a- 11 = -2a+ 4
a+ 2a= 11+ 4
3a = 15 I 3
a = 5
x- 2= 5 x- 2= - 5
x = 5+ 2 x = - 5+ 2
x = 7 x = -3
S= { -3; 7}
b. - 2Ix+ 3I+ 4I x+ 3I= 15- 5I x+ 3I- 1 I x+ 3I = a
-2a+ 4a= 15- 5a- 1
+ 2a+ 5a= 14
7a = 14 I : 7
a = 2
x+ 3= 2 x+ 3= - 2
x = 2- 3 x = - 2- 3
x = - 1 x = -5
S = { -5; -1}
c. 3I x+ 1I+ 5 = I x+ 1I + 11 Ix+ 1I = a
3a+ 5= a+ 11
3a- a= 11- 5
2a = 6 I:2
a = 3
x+ 1= 3 x+ 1= - 3
x = 3- 1 x = - 3- 1
x = 2 x = -4
S = { -4; 2}
d. - 4I2x- 1I+ 2= - I2x- 1I- 7 I2x- 1I = a
-4a+ 2= -a- 7
+2+ 7= 4a-a
9= 3aI :3
3 = a
2x-1= 3 2x- 1= - 3
2x = 3+ 1 2x = - 3+ 1
2x = 4I: 2 2x = -2 I: 2
x = 2 x= -1
S = { -1; 2}