Question

sa se afle numerele a,b,c stiind ca indeplinesc pe rand urmatoarele conditii:a+2b=47,b+2c=55 si c+2a=45

Answer 1

a + 2b = 47
b + 2c = 55
c + 2a = 45

a=47-2b
b=55-2c
c=45-2a

a + 2(55-2c) = 47
a + 110 - 4c = 47
a + 110 - 4 (45-2a) = 47
a + 110 - 180 + 8a = 47
9a - 70 = 47
9a = 70 + 47 
9a = 117 
a = 117 : 9 
a = 13

13 + 2b = 47
2b = 47 - 13
2b = 34
b = 34 : 2 
b= 17 

c + 26 = 45
c = 45 - 26
c= 19 

Answer 2

a + 2b = 47 , a = 47 - 2b
b + 2c = 55    b = 55 - 2c
c + 2a = 45    c = 45 - 2a

3a + 3b + 3 c = 147
3 ( a + b + c ) = 147
a + b + c = 147 : 3
a + b + c =49
47 - 2b + b + c = 49
47 - 2b + b + 45 - 2a = 49
47 - 2b + b + 45 - 2 x ( 47 - 2b ) = 49
47 - 2b + b + 45 - 94 + 4b = 49
3b = 49 - 47 - 45 + 94
3b = 51
b = 51 : 3
b = 17
a = 47 - 2b
a = 47 - 2 x 17
a = 47 - 34
a = 13
c = 45 - 2a
c = 45 - 2 x13
c = 45 - 26
c = 19