Question

How many solutions does the system have?
y = 3x + 9
y = -1/2x - 1

Answer 1

Set the first function equal to the second function:
3x + 9 = -1/2 - 1
And solve for x :)

Answer 2

there is different slopes and different y intercepts......I would say 1 solution......but wait and see what phi says...he is smarter then me

Answer 3

notice that both equations are equations of a line

if two lines are not parallel (i.e. do not have the same slope) they meet only once (where they cross)

Answer 4

and to be the clear, the (x,y) point that is on both lines (where the cross) is *the* solution

Answer 5

well said, phi :)

Answer 6

1 exception is of both equations are a different equation for the exact same line, in which case the lines have infinite solutions (they are literately on top of each other, so they always cross)