00:01
Suppose i have a system of equations.
00:02
I have three equations, three different variables, so the system can be solved.
00:06
My goal is to solve for a, b and c.
00:09
First i see, let's compose this into a system of two equations with two variables.
00:13
I have b is equal to 5c minus 2a minus 1.
00:17
So i could replace b in each of these equations.
00:20
So 3a equals 5 times the entire expression minus c minus 19.
00:29
And i could simplify this.
00:30
I could distribute 5.
00:31
To each term first, right parentheses, 25c minus 10a minus 5 minus c minus 19.
00:38
What i could do is get all my variable terms to one side, so add 10a to both sides.
00:46
Combine my c, so 13a equals 25 minus 1c is 24c, negative 5 minus 19 minus 24, and then subtract 24c from both sides.
01:01
Then my expression, i can't combine a and c because there are two different variables.
01:06
It equals negative 24.
01:08
So this is my new expression, 13.
01:12
A minus 24c equals negative 24.
01:15
And then i'm also going to replace b in this equation.
01:18
So 7a plus 3 times what b is 5c minus 2a minus 1 plus c equals 13.
01:31
Okay.
01:32
Distribute the 3, so this would be 15c minus 6a minus 3...