Answer: a = 17/2 and b =1/2 and c = 6
Step-by-step explanation:
the system is : a+b=9...........(1)
2b+2c=13 .......(2)
2a-c=11 ...........(3)
by (1) and (2) calculate : a and b
by (3) : 2a = 11 +c
so : a = (11+c)/2.....( *)
by (2) : 2b = 13 -2c
so : b =(13-2c)/2......(**)
put the value for a and b by (*) and (**) in (1) :
(11+c)/2. + (13-2c)/2 = 9
(11+c +13-2c)/2 = 9
24-c =18
c = 24-18
c = 6
put this value in (*) and (**)
a = (11+6)/2
a = 17/2
b = (13-12)/2
b =1/2
yoi can verify : 1) a+b = 9 : 17/2 +1/2 = 18/2 = 9 .....right
2) 2b+2c=13 : 2(1/2)+2(6) =1+12 = 13 .....right
3) 2a-c=11 : 2(17/2)-6 =17-6 = 13.......right
