Question 328607
"sketch the plane defined by the equation 2x+y-z=10" 
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Sketch the xyz system, usually it's y + to the right, z + up, and x about 45º down and to the left.
Find the intercepts:
when x&y = 0, z = -10.  Plot that point on the z-axis
when x&z = 0, y = +10.  Plot that on the y-axis
when y&z = 0, x = + 5.  Plot that one.
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Connect the 3 points with lines, then you might try to shade the plane.
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dl MathGV from mathgv.com, it might help, might not.