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Mathematics 19 Online
OpenStudy (amd011802):

Graph the piecewise function.

OpenStudy (amd011802):

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OpenStudy (amd011802):

@peachpi

OpenStudy (amd011802):

this one im completely confused on

OpenStudy (phi):

can you plot y= 3x -5 ?

OpenStudy (amd011802):

i dont know what im supposed to do on this problem.

OpenStudy (phi):

you plot 3 lines but the lines don't go on forever. The first step is plot y= 3x-5 then erase the part where x is bigger than -1 can you do that ?

OpenStudy (amd011802):

im confused by what you just said. im sorry

OpenStudy (phi):

do you know how to plot the line y= 3x-5 (answer is yes or no)

OpenStudy (amd011802):

no

OpenStudy (phi):

pick a number for x, for example x=-1 then figure out y using y= 3* -1 -5 can you find y ?

OpenStudy (amd011802):

i got y=-8 is that correct?

OpenStudy (phi):

yes, so we know (-1, -8) is a point on the line can you plot that point ?

OpenStudy (amd011802):

okay i did that whats next

OpenStudy (phi):

we need one more point, and then we draw a line through the two points we should try x=-2 can you find y when x= -2, using y= 3x-5

OpenStudy (amd011802):

y= -11

OpenStudy (phi):

yes ,so another point is (-2, -11)

OpenStudy (amd011802):

now what?

OpenStudy (phi):

next, if we look at what they say \[ y= 3x -5, \text{ } x\le -1\] that says the line goes forever toward minus infinity, but it stops at x=-1 and because of the \( \le\) (i.e. the less than or equal) the line includes the point (-1,-8) so we put a solid dot at that point.

OpenStudy (phi):

It should look something like this:

OpenStudy (amd011802):

yes thats what i have so far

OpenStudy (phi):

now we do the next line y= -2x +3 for -1 < x < 4 we plot that line, but only between x= -1 and x=4 I would find the y value for x=-1 plot that point. (But use an *open circle* to show that the point is not part of the line) ditto for x=4 can you find those two points ?

OpenStudy (amd011802):

(-1,5) and (-4,11)

OpenStudy (phi):

ok on the first point. but the second one should use x=4 (not -4) (see the original problem)

OpenStudy (amd011802):

oh sorry (4,-5)

OpenStudy (phi):

now plot those 2 points with OPEN circles because though they are the end points of the line the "less than" x < 4 means x is not allowed to be 4 (so the point 4,-5 is not part of the line)

OpenStudy (phi):

It should look like this

OpenStudy (amd011802):

okay got that

OpenStudy (phi):

the last part is y=2 for x>= 4 that is a horizontal line at y=2 with a SOLID dot at (4,2) and the line goes to the right forever.

OpenStudy (amd011802):

is that it?

OpenStudy (phi):

yes, it should look like this

OpenStudy (phi):

ok ?

OpenStudy (amd011802):

thank you so much

OpenStudy (phi):

yw

OpenStudy (amd011802):

i gave you a medal

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