Question

Solve the system for A,B, and C:
{A+B+C=0;
7A+4B+C= -26
10A-5B-2C = -47}

Answer 1

What do yu think you should use, the elimination method or substitution?

Answer 2

I'll give you a hint, look at + C and -2C

Answer 3

you can use the matrix method if you know it, its faster and easier, otherwise follow comp. advise

Answer 4

ISutts, I'm not going to solve it for you, I'm going to work with you and teach you how to solve it. So please reply or I will no longer follow this thread.

Answer 5

i don;t know either method

Answer 6

and i have the answers of a = 6, b = -1 and c= -4, but how is what i want to know

Answer 7

let
A+B+C=0.............(i)
7A+4B+C= -26........(ii)
10A-5B-2C = -47..............(iii)
we'll use substitution method.
from (i) C = 0 -(A+B) = -A-B
substitute this in (ii) and (iii)
(ii) therefore becomes 7A +4B-A-B = -26 ;
it reduces to 6A-3B = -26
(iii) becomes 10A - 5B -2(-A-B) = -47 ;
it reduces to 12A - 3B = -47
do you see the common 3B in (ii) and (iii)
subtract (ii) from (iii)
12A-6A-3B--3B = -47 -- 26
6A = -21
A = -3.5
B = -15 2/3
C = 19 1/6
Thoat's how to do it and those are these correct answers