4a-2b+3c=21
a+4b-5c=-3
5a-3b-2c=8
it said that the answers for B&C are either 1,2,3,4.
I tried adding all & checking each answer w/it..but the fact that "A" is unk. is k*****g me.
+130511 4a-2b+3c=21 (1)
a+4b-5c=-3 (2)
5a-3b-2c=8 (3)
Multiply equation (2) by -4 and add it to equation (1) ...this gives....
4a -2b +3c= 21
-4a -16b+20c= 12
---------------------
-18b + 23c = 33 (4)
Now, multiply equation (2) by -5 and add it to equation (3)
-5a-20b+25c=15
5a -3b -2c= 8
--------------------
-23b + 23c = 23 → -b + c = 1 (5)
Now, using (4) and (5) we have
-18b + 23c = 33
- b + c = 1
Multiply (5) by -18 and add it to (4)
-18b + 23c = 33
18b - 18c = -18
---------------------
5c = 15
c = 3
So using -b + c = 1 ..we have..... -b + 3 = 1 → -b = -2 → b =2
And using (2), we have.....
a+4(2)-5(3)=-3
a + 8 - 15 = -3
a - 7 = -3
a = 4
So...our solutions are a= 4 b = 2 and c = 3
+130511 4a-2b+3c=21 (1)
a+4b-5c=-3 (2)
5a-3b-2c=8 (3)
Multiply equation (2) by -4 and add it to equation (1) ...this gives....
4a -2b +3c= 21
-4a -16b+20c= 12
---------------------
-18b + 23c = 33 (4)
Now, multiply equation (2) by -5 and add it to equation (3)
-5a-20b+25c=15
5a -3b -2c= 8
--------------------
-23b + 23c = 23 → -b + c = 1 (5)
Now, using (4) and (5) we have
-18b + 23c = 33
- b + c = 1
Multiply (5) by -18 and add it to (4)
-18b + 23c = 33
18b - 18c = -18
---------------------
5c = 15
c = 3
So using -b + c = 1 ..we have..... -b + 3 = 1 → -b = -2 → b =2
And using (2), we have.....
a+4(2)-5(3)=-3
a + 8 - 15 = -3
a - 7 = -3
a = 4
So...our solutions are a= 4 b = 2 and c = 3
