Question 32099This question is from textbook Beginning and Intermediate Algebra
: My question is this: 2y-x<8
I have turned it around to be -x+2y=8 and found the first set of ordered pair to help graph. x,0,y,4 But my book says the next ordered pair is -8x and 4y. I would like to know why? How did they get the second pair? I know that because of < it is a slashed line when you graph.
Any help would be greatly appreciated.
Thanks, Liz
This question is from textbook Beginning and Intermediate Algebra
Answer by venugopalramana(3286)   (Show Source):
You can put this solution on YOUR website! SEE MY COMMENTS BELOW
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My question is this: 2y-x<8...THIS IS AN INEQUALITY...OK WHAT ARE YOU SUPPOSED TO DO ?SOLVE IT?OR PLOT IT?WHAT IS THE TASK.LET US SAY YOU ARE TO PLOT IT..OK...
I have turned it around to be -x+2y=8
YOU PUT EQUAL TO,.... TO DRAW A LINE WHICH SEPERATES THE 2 ZONES OF -X+2Y<8 AND
-X+2Y>8..OK....
and found the first set of ordered pair to help graph. x,0,y,4...OK....
But my book says the next ordered pair is -8x and 4y.
FIRSTLY THERE IS NOTHING LIKE A UNIQUE SECOND ORDERED PAIR.YOU CAN TAKE ANY SUITABLE PAIR AS FIRST,SECOND ETC..OK...HAVING SAID THAT THE ORDERED PAIR CANNOT BE -8X AND 4Y..IT COULD BE LIKE AS YOU DID FIRST ,-8,8 WHICH SATISFIES -X+2Y=8
SO CHECK AND INFORM WHAT IS REQUIRED...
NOW SUPPOSE YOU USED THESE 2 POINTS TO DRAW THE GRAPH AS GIVEN BELOW,NEXT TASK IS TO IDENTIFY WHICH ZONE OR WHICH SIDE OF THE LINE IS -X+2Y<8 AS IS REQUIRED SAY...THEN YOU WILL TEST ONE POINT ..EASIEST IS 0,0..YOU WILL FIND THAT -0+2*0=0<8...SO ORIGIN 0,0 LIES IN THE REQUIRED ZONE SO MARK ALL AREA FROM THE LINE TOWARDS ZERO BY HATCHING AND WRITE IT AS THE REQUIRED ZONE.
I would like to know why? How did they get the second pair? I know that because of < it is a slashed line when you graph.
Any help would be greatly appreciated.
Thanks, Liz
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