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

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."