Question

.ajutati-ma ... va rog​

Answer 1

K) [(2x3x5)^2-8^4:8^2]:2^2-4x5x6=
[30^2-8^2]:2^2-120=
[900-64]:2^2-120=
836:4-120=
209-120=
= 89

L) (28,5-25,8):12+9,8=
(285/10-258/10):12+98/10=
(285-258/10):12+49/5=
(27/10):12+49/5=
(27/10)x1/12+49/5=
(9/40)+49/5=
9/40+49/5=
9+392/40=
= 401/40

N) (450x10:100)+(200x5:100)-(100x7:100)=
45+10-7=
55-7=
= 48

O) 28/31x[1/4+(2x1/2-7/4):7/8]=
28/31x[1/4+(1-7/4):7/8]=
28/31x[1/4+(4-7/4):7/8]=
28/31x[1/4+(-3/4):7/8]=
28/31x[1/4+(-3/4)x(4x2/7)]=
28/31x[1/4+(-6/7)]=
28/31x[7+(-6x4)/4x7]=
28/31x[-17/28]=
(28/31)x(-17/28)=
= -17/31

P) (3+1/2)x(5/11+1/7)x(4+3/2)=
((3x2)+1/2)x((5x7)+11/11x7)x((4x2)+3/2)=
(7/2)x(46/77)x(11/2)=
23/11x(11/2)=
= 23/2


Q) 5x5/8x(3x2/5+2x1/15-3x1/3)=
25/8x((6x3)+2/5x3)=
25/8x(4/3-1)=
25/8x(4-3/3)=
25/8x(1/3)=
= 25/24

R) 1/5+6x{1x1/5-2x[1/3-3/2x(1/5-1/6)]}=
25/8x((6x3)+2/5x3-3x1/3)=
25/8x(4/3-1)=
25/8x(4-3/3)=
25/8x(1/3)=
= 25/24

Exercițiul 2
A) 2(3x-1)+7= 35
6x-2+7= 35
6x+5= 35
6x= 35-5
6x= 30
X= 30/6
X= 5

B) [3(2x-7)+11]:2-9= 1
[3(2x-7)+11]:2= 10
3(2x-7)+11= 20
3(2x-7)= 9
6x-21= 9
6x= 30
X= 30:6= 5

C) 0,2(2,5x-7,5)-2,7= 1,3
(1/5)•(5/2x-15/2)-(27/10)-{(13/10)}= 0
(1/2x-3/2)-(27/10)-{(13/10)}= 0
(1/2x-21/5)-{(13/10)}= 0
1/2x-11/2= 0
(1/2)•x+(-11/2)= 0
X= 11

D) (2x-3)•6= 54-6x
12x-18= 54-6x
12x+6x= 54-6x
18x= 72
X= 72:18
X= 4

E) 512:(9x-19)-4= 120:2
512:(9x-19)-4= 60
512:(9x-19)= 60+4
512:(9x-19)= 64
9x-19= 512:64
9x-19= 8
9x= 8+19
9x= 27
X= 27:9=
X= 3

F) 3•[3•(3x+7)+10]+11= 374
3•[3•(3x+7)+10]= 374-11
3•[3•(3x+7)+10]= 363
[3•(3x+7)+10]= 363/3
3•(3x+7)+10= 121
3•(3x+7)= 121-10
3•(3x+7)= 111
3x+7= 111/3
3x+7= 37
3x= 37-7
3x= 30
x= 30/3
x= 10

G) 59x-508= 49x+102
10x-610= 0
(10)•x+(-610)= 0
-610/10=
X= 61

H) [72:(48-x)+58]:10= 13
72:(48-x)+58= 13•10
72:(48-x)+58= 130
72:(48-x)= 130-58
72:(48-x)= 72
48-x= 72/72
3456-72x= 72
-72x= 72-3456
-72x= -3384
x= 3384/72.
1692/36

I) 2^x-16= 2^4
2^x-16= 16
2^x= 32
x= 32/2
x= 5

Exercițiul 3
37/25= 1,48

43/3= 14,3

7/3= 2,3

39/25= 1,56

47/6= 7,83

11/3= 3,6

Exercițiul 4
23/10
27/100
26/100
47/10
81/100
46/100

Exercițiul 5
Calculați 30% din 700
3•7= 21

Exercițiul 6
32,24+34,36= 66,6
28,57-38,32= -9,75
66,6+9,75= 56,85

Exercițiul 7
Aflați trei numere daca media aritmetică a câte doua dintre ele este: 80,13;97,89;105,66
(a+b)/2= 80,13
(b+c)/2= 97,89
(a+c)/2= 105,66

a+b= 2x80,13= 160,26
b+c= 2x97,89= 195,78
a+c= 2x105,66= 211,32

2x(a+b+c)= 160,26+195,78+211,32= 567,36
a+b+c= 567,36:2
a+b+c= 283,68 sumă celor 3 numere

283,68-195,78= 87,9 (a) primul număr
160,26-87,9= 72,97 (b) al doilea număr
211,32-87,9= 123,42 (c) al treilea număr

V: (87,9+72,97):2= 160,87:2= 80,435 media aritmetică a primelor două numere
(72,97+123,42):2= 196,39:2= 98,195 media aritmetică ultimelor două numere