Question

Need help pls! @ganeshie8 @Jhannybean @Directrix @mathmath333

Answer 1

i got n=3 and m=-2

Answer 2

How did you get those answers? Using x and y-intercepts maybe as points on the graph, maybe?

Answer 3

https://www.desmos.com/calculator/rtgszh3mgq

Answer 4

please, notethat, your equation can be rewritten as below:
\[y=mx+n\]
if mx+n is greater or equal to 0
and \[y=-mx-n\]
if mx+n is less than zero.
Now from first case we have to solve this inequality:
mx+n>=0,
from your graph I see that the solution has to be x>0 because x=3/2.
So the above inequality has solution if and only if m>0 because after i dived by m, I get:
\[x \ge \frac{ -n }{ m }\]
SImilar discussion is going for the second case, namely
mx+n<0,
or
mx<-n
which is possible if and only if m is positive, so we can get
\[x <\frac{ -n }{ m }\]
in conclusion, all that we can say is:
\[\frac{ -n }{ m }=\frac{ 3 }{ 2 }, m>0\]

Answer 5

@MARC_

Answer 6

even if m<0 can be a solution too!

Answer 7

Using the points, (1.5, 0) and (0,3) from the graph, I set equations


0 = abs(m* (1.5) + n)
3 = abs(0 + n)
----------------
to solve simultaneously.

Answer 8

Realizing, of course, that absolute value is tricky when variables are involved.

Answer 9

right! If I use the point (0,3), I can stes completely the solution, because, now I know that n=3 and m=-2

Answer 10

oops ...I can state...

Answer 11

I have two sets of answers for (m,n) but I have not yet attempted to interpret them in the context of this problem.

(m,n)
====

(-2, 3)
(2, -3)

I am not saying that they are correct. @MARC_ should take a look at our work and ideas.

Answer 12

@MARC_ posted these: >>i got n=3 and m=-2

Answer 13

please note that n=3 is the only solution acceptable, even if there is the other solution, namely n=-3. Nevertheless in the graph there is no line with n=-3

Answer 14

Right. That is exactly what I want @MARC_ to realize: the what and the why.

Answer 15

if this was not 'abs' function then you can see that the intercept would be -3, and the slope 2

This function becomes negative when 2x=3, i.e. x=1.5

so when the 'abs' is taken into account it becomes the graph oyu see

Answer 16

so @Michele_Laino I do not agree that n=3 is the correct soluyion

Answer 17

Thanks! @Directrix

Answer 18

plot y= 2x-3
then plot y = abs(2x-3)

Answer 19

abs(2x-3) = abs(-2x+3)

Answer 20

https://www.desmos.com/calculator/zpyfderfst

Answer 21

@MARC_ I got the same

Answer 22

This was my working...
\[y=mx+n\]
\[y=m(0)+n\]

Answer 23

\[y=n\]

Answer 24

\[n=3\]

Answer 25

\[y=mx+n\]

Answer 26

\[0=mx+n\]
\[-n=mx\]

Answer 27

\[-(3)=m(\frac{ 3 }{ 2 })\]

Answer 28

\[-6=3m\]
\[m=-2\]

Answer 29

but the real answer is m=2 and n=-3
@Directrix @MrNood @mathmath333 @Michele_Laino @triciaal

Answer 30

Thnx @Directrix @Michele_Laino @MrNood @mathmath333 @triciaal

Answer 31

Thanks! @MARC_

Answer 32

@MARC_
m=-2 n=3 is an equally valid solution - as shown above they produce exactly the same result