Question

Based on the lesson, which of the following would be the best approach for solving this system by substitution?

5x = y + 6
2x - 3y = 4

Solve the first equation for x.
Solve the first equation for y.
Solve the second equation for x.
Solve the second equation for y.

Answer 1

usually you substitute what is easiest to make the subject

since 5x = y - 6 is one step away from having y as the subject, this is the easiest one.
so you will get y = 5x + 6 and sub this into the second eqn. When you do so, the y disappears (as it gets subbed for something involving x) so you end up with the second equation turning into an equation to solve for x only.