<body><script type="text/javascript"> function setAttributeOnload(object, attribute, val) { if(window.addEventListener) { window.addEventListener('load', function(){ object[attribute] = val; }, false); } else { window.attachEvent('onload', function(){ object[attribute] = val; }); } } </script> <div id="navbar-iframe-container"></div> <script type="text/javascript" src="https://apis.google.com/js/plusone.js"></script> <script type="text/javascript"> gapi.load("gapi.iframes:gapi.iframes.style.bubble", function() { if (gapi.iframes && gapi.iframes.getContext) { gapi.iframes.getContext().openChild({ url: 'https://www.blogger.com/navbar.g?targetBlogID\x3d14084555\x26blogName\x3dPre-Cal+30S\x26publishMode\x3dPUBLISH_MODE_BLOGSPOT\x26navbarType\x3dBLUE\x26layoutType\x3dCLASSIC\x26searchRoot\x3dhttp://pc30s.blogspot.com/search\x26blogLocale\x3den_US\x26v\x3d2\x26homepageUrl\x3dhttp://pc30s.blogspot.com/\x26vt\x3d931551856370134750', where: document.getElementById("navbar-iframe-container"), id: "navbar-iframe" }); } }); </script>

Wednesday, November 09, 2005

Scriber's Post



Mr. K started the class by posting up 2 problems on the board;
sketch each pair of lines on the same cartesian plane:
1.) x+y=4
x-y=-2


2.) x+2y=1

x-y=4



while sketching those lines on the cartesian plane, Mr. K moves around the room to tell everyone
their mark for the first term. he then explain to us how to do the problems on the board.



1.





transfer each equation into slope-intercept form (y=mx+b)

x+y=4

y=-x+4

*slope=-1/1 y int.=4





x-y=-2

-y=-x-2

y=x+2

*slope=1 y int.=2





2.





x+2y=1

2y=-x+1

y=-x+1

  2

*slope=-1/2 y int.=1/2





x-y=4

-y=-x+4

y=x-4

*slope=1 y int.=-4





after doing those, Mr. K change the equal sign in every equation and we need to graph them
again.



they are as follows:



1.) x-y≥4

x-y<-2



2.) x+2y≤1

x-y≥4





this new topic is called Linear Inequalities



before giving the answers to the problems, its better to explain first what is linear
inequalities is about.



-a linear inequality is very similar to an equation, except with " <,>,≤?? & ≥?? " in place
of " = ".



*rule- when you multiply or divide by a negative number, the sign flips.



ex. 3x-2y≥4



-2y≥-3x+4



-2y-3x+4



-2 -2



y≤3x-2



2





when graphing the line, remember that an equation with < & > should be a dashed line
(<------------->)



if the sign is either & ≥, the line should be a straight line(<_____________>)



dash line means that the line is not included in the solution for the equation and a
straight line means that the line is included in the solution for the equation.





back to the problems:



1.





it would be easy to graph these problems in the calculator.





x+y≥4



x-y<-2



in order for you to know the part to be shaded, you need to graph the lines first by
changing the signs into equal sign.



after that you can pick a point from the graph (x,y) ; either at the right or at the left of the
line. if the point satisfy the equation, that means that you need to shade the part where the
point you pick is located. if it doesn't satisfy the equation, shade the other side of the line.



lets pick one of the equation to be an example:



x+y≥4



(0)+(0)≥4 pick up any easy number to replace the value of x and y. in this equation, I
pick up the value of the origin.(0,0)



0≥4 because in truth 0 can never be greater than 4, it means that the solutions
for the equation is in the other side of the line where the origin is



not located.





2.





x+2y≤1



x-y≥4





remember that if a dash line intersect a straight line, mark the point of intersection with
an open dot (o)



-straight line intersect a straight line, mark with a coloured dot (∙??)



-dash line intersect a dash line, mark with an open dot (o)





if you want to know (and you have the patience to read) how to graph inequalities into
your calculator, visit this site E:\data\Guidebooks\Applications\Mathematics\InEquality
Graphing\English\inequal.pdf





thats it for my scribe. sorry for posting this up so late, im just having trouble uploading pictures earlier. tomorrows scribe is jessica l.





1 Comments:

At 11/10/2005 5:29 PM, Blogger AichelleS. said...

wow that's awesome haha grrrreat job

 

Post a Comment

Links to this post:

Create a Link

<< Home