Question

4a+2b+c=10
100a+10b+c=12
16a+4b+c=12

I need help to solve this problem. I keeping getting A=1.70 B=2.0 and C=5. My book says that is wrong, could you show me how to get the correct answer?

Answer 1

If we call the equations #1,2,3 then subtract #1 from #2 and #3 from #3 to get

96a + 8b = 2
84a + 6b = 0

So, 6b = -84a, meaning 8b = -112a

So,

96a - 112a = 2
-16a = 2
a = -1/8
now use that to get
b = 7/4
c = 7

It would have been nice for you to have shown your work. Oh well, maybe you can use the above logic to discover your error.