document.write( "Question 116283: Can you help me with these questions? I did not get this out of a book, it was a handout. The question is: Find the x and y intercepts and then graph
\n" ); document.write( " x-y=2 , -x+4y=4 and y = -4x -4. I do not fully understand the question.
\n" ); document.write( "Any help on this is greatly appreciated. Can you explain it step by step, not leaving anything out , please.\r
\n" ); document.write( "\n" ); document.write( "Thankyou
\n" ); document.write( "Laurie
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Algebra.Com's Answer #84587 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
:
\n" ); document.write( "I will try to be very detailed on the 1st one, hopefully by the time you get to the 2nd one you will have an idea what's going on.
\n" ); document.write( ":
\n" ); document.write( "Find the x and y intercepts and then graph
\n" ); document.write( ":
\n" ); document.write( "x - y = 2
\n" ); document.write( "First we want to put the equation in the \"y =\"; subtract x from both sides:
\n" ); document.write( "-y = -x - 2
\n" ); document.write( "y has to be positive in this form, multiply equation by -1 and you have:
\n" ); document.write( "y = x + 2
\n" ); document.write( ":
\n" ); document.write( "The x intercept occurs when y = 0, therefore make y = 0 and solve for x:
\n" ); document.write( "x + 2 = y
\n" ); document.write( "x + 2 = 0
\n" ); document.write( "x = -2; this is the x intercept
\n" ); document.write( ":
\n" ); document.write( "The y intercept occurs when x = 0; substitute 0 for x in our equation, find y:
\n" ); document.write( "y = x + 2
\n" ); document.write( "y = 0 + 2
\n" ); document.write( "y = +2; this is the y intercept
\n" ); document.write( ":
\n" ); document.write( "To graph this we need at least two x,y points, choose convenient values for x:
\n" ); document.write( " let x = -3 and let x = +3
\n" ); document.write( ":
\n" ); document.write( "Substitute -3 for x:
\n" ); document.write( "y = x + 2
\n" ); document.write( "y = -3 + 2
\n" ); document.write( "y = -1
\n" ); document.write( "Plot x=-3, y=-1 on a standard +/-10 graph
\n" ); document.write( ":
\n" ); document.write( "2nd point: x = +3
\n" ); document.write( "y = x + 2
\n" ); document.write( "y = 3 + 2
\n" ); document.write( "y = +5
\n" ); document.write( "Plot x=3, y=5 on the same graph, join points with a straight line, this is the graph
\n" ); document.write( ":
\n" ); document.write( "Should look like this
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-5%2C+5%2C+-5%2C+5%2C+x%2B2%29+\"
\n" ); document.write( "Note that it confirms are values for the x and y intercepts
\n" ); document.write( "The graph crosses the vertical line where y=2, (the y intercept)
\n" ); document.write( "The graph crossed the horizontal line where x = -2; (the x intercept)
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\n" ); document.write( ":
\n" ); document.write( "-x + 4y = 4
\n" ); document.write( "Put equation into the y= form, add x to both sides
\n" ); document.write( "4y = x + 4
\n" ); document.write( "y has to have a coefficient of 1, divide both sides by 4 and you have:
\n" ); document.write( "y = \"x%2F4\" + \"4%2F4\"
\n" ); document.write( "y = .25x + 1
\n" ); document.write( ":
\n" ); document.write( "The x intercept (y=0):
\n" ); document.write( ".25x + 1 = y
\n" ); document.write( ".25x + 1 = 0
\n" ); document.write( ".25x = -1
\n" ); document.write( "x has to have a coefficient of 1, multiply both sides by 4 and you have;
\n" ); document.write( "x = -4; is the x intercept
\n" ); document.write( ":
\n" ); document.write( "The y intercept (x=0)
\n" ); document.write( "y = .25x + 1
\n" ); document.write( "y = .25(0) = 1
\n" ); document.write( "y = 0 + 1
\n" ); document.write( "y = 1 is the y intercept
\n" ); document.write( ":
\n" ); document.write( "two x,y points, choose some convenient values for x:
\n" ); document.write( " let x = -3 and let x = +3
\n" ); document.write( ":
\n" ); document.write( "Substitute -3 for x:
\n" ); document.write( "y = .25x + 1
\n" ); document.write( "y = .25(-3) + 1
\n" ); document.write( "y = -.75 + 1
\n" ); document.write( "y = +.25
\n" ); document.write( "Plot x=-3, y=+.25
\n" ); document.write( ":
\n" ); document.write( "2nd point: x = +3
\n" ); document.write( "y = .25(3) + 1
\n" ); document.write( "y = .75 + 1
\n" ); document.write( "y = +1.75
\n" ); document.write( "Plot x=3, y=1.75 on the same graph, join points with a straight line, this is the graph.
\n" ); document.write( ":
\n" ); document.write( "Should look like this
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-5%2C+5%2C+-5%2C+5%2C+.25x%2B1%29+\"
\n" ); document.write( "Note that it confirms are values for the x and y intercepts
\n" ); document.write( "The graph crosses the vertical line where y=1, (the y intercept)
\n" ); document.write( "The graph crossed the horizontal line where x = -4; (the x intercept)
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "y = -4x - 4 this one is already in the form we want it:
\n" ); document.write( ":
\n" ); document.write( "x intercept (y=0)
\n" ); document.write( "-4x -4 = y
\n" ); document.write( "-4x - 4 = 0
\n" ); document.write( "-4x = +4; added 4 to both sides:
\n" ); document.write( "x = -1; divided both sides by -4 to make the coefficient of x a +1
\n" ); document.write( ":
\n" ); document.write( "y intercept (x=0)
\n" ); document.write( "y = -4(0) - 4
\n" ); document.write( "y = -4;
\n" ); document.write( ":
\n" ); document.write( "Graph this equation the same way, it is more convenient to use x = -2 and x = +1
\n" ); document.write( "This is to keep the points on a +/-10 xy graph.
\n" ); document.write( "Substitute -2 for x:
\n" ); document.write( "y = -4x - 4
\n" ); document.write( "y = -4(-2) - 4
\n" ); document.write( "y = +8 - 4
\n" ); document.write( "y = +4
\n" ); document.write( "Plot x=-2, y=+4
\n" ); document.write( ":
\n" ); document.write( "2nd point: x = +1
\n" ); document.write( "y = -4(1) - 4
\n" ); document.write( "y = -4 - 4
\n" ); document.write( "y = -8
\n" ); document.write( "Plot x=1, y=-8 on the same graph, join points with a straight line,
\n" ); document.write( ":
\n" ); document.write( "Should look like this
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-5%2C+5%2C+-5%2C+5%2C+-4x-4%29+\"
\n" ); document.write( "Note that it confirms are values for the x and y intercepts
\n" ); document.write( "The graph crosses the vertical line where y=-4, (the y intercept)
\n" ); document.write( "The graph crossed the horizontal line where x = -1; (the x intercept)
\n" ); document.write( ":
\n" ); document.write( "It tried to make things clear here, if you have any questions about this concept you can email me. A
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