Mathematics
6 Online
OpenStudy (gabylovesyou):
Which of the following inequalities matches the graph?
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OpenStudy (gabylovesyou):
-6x + y < 3
6x + y < 3
6x - y < -3
The correct inequality is not listed
OpenStudy (gabylovesyou):
@helder_edwin
OpenStudy (helder_edwin):
can u see that the point (-4,2) is in the shaded area?
OpenStudy (gabylovesyou):
yes
OpenStudy (helder_edwin):
(this point is arbitrary, u could have chosen any point in the shaded area)
then u have x=-4 and y=2.
now replace these in every inequality u r given
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OpenStudy (helder_edwin):
for instance
\[ \large -6x+y<3 \]
\[ \large -6(-4)+2<3 \]
\[ \large 24+2<3 \]
\[ \large 26<3 \]
is this true?
OpenStudy (helder_edwin):
it is not.
OpenStudy (helder_edwin):
then pass to the second
OpenStudy (helder_edwin):
\[ \large 6x+y<3 \]
\[ \large 6(-4)+2<3 \]
\[ \large -24+2<3 \]
\[ \large -22<3 \]
is this true?
OpenStudy (gabylovesyou):
true
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OpenStudy (helder_edwin):
how about the third one?
\[ \large 6x-y<-3 \]
\[ \large 6(-4)-2<-3 \]
\[ \large -24-2<-3 \]
\[ \large -26<-3 \]
is this true?
OpenStudy (helder_edwin):
also true
OpenStudy (helder_edwin):
then u have two possible answers
\[ \large 6x-y<-3 \]
or
\[ \large 6x+y<3 \]
OpenStudy (gabylovesyou):
but which one matches the graph?
OpenStudy (helder_edwin):
do u see the line that limits the shaded area?
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OpenStudy (gabylovesyou):
yes
OpenStudy (helder_edwin):
does it have positive or negative slope?
OpenStudy (gabylovesyou):
from left to right??
OpenStudy (helder_edwin):
positive slope
OpenStudy (gabylovesyou):
yes :)
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OpenStudy (helder_edwin):
if we write = instead of < then
\[ \large 6x+y=3\Rightarrow y=-6x+3 \]
negative slope
OpenStudy (helder_edwin):
but
\[ \large 6x-y=-3\Rightarrow y=6x+3 \]
positive slope
OpenStudy (helder_edwin):
then the answer is
\[ \large 6x-y<-3 \]
OpenStudy (gabylovesyou):
ohhh so its C :)
OpenStudy (gabylovesyou):
Thank you !! (;
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OpenStudy (helder_edwin):
u r very welcome