Part 1 : When solving systems of equations, how do you determine what method to use?

Part 2 : Choose 1 system of equations from the choices below. Then, solve the system and post your solution, showing your steps so that other students can see which method you chose.

-y + 3x = 6

y = - 6x + 12

6x - 4y = 54

-9x + 2y = - 69

2y = x + 1

-2x - y = 7

... ?

Part 1. The selection of method to use for solving system of equations is a matter of arbitrary choice. That is, what's convenient for you. For me, elimination is easier.

Part 2. I'll try solving the second system. 6x-4y = 54-9x+2y = - 69

Multiplying the first equation by 9 and the second equation by 6.

54x - 36y = 486-54x + 12y = - 414

Adding the two equations,

-24y = 72y = - 3

Subtitute back to one of the equations,-9x + 2y = - 69-9x + 2 (-3) = - 6969 - 6 = 9x9x = 63x = 7

The solution is then (7, - 3).