Question #35ec7

1 Answer
Tony B
May 13, 2017

Intercept for #" "y-y=2x" "->(x,y)->(0,-8)#
Intercept for #" "y=2x" "->(x,y)=(-8/5,-16/5)#

Explanation:

#color(blue)("Assumption: The question as given is correct")#

This is an exercise in thinking before you leap.

Consider the equation: #y-y=2x#

This is the same as #0=2x=>x=0#

Note that #x=0# is the y-axis. So the question is really asking:

What is the y-intercept for #3x+y=-8#?

Consider: #3x+y=-8#

Subtract #3x# from both sides

#y=-3x-8#

Set #x=0# giving:

#y=-8#

So the intercept is #(x,y)->(0,-8)#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Assumption: The question as given is not correct")#
Suppose the given #y-y=2x# was meant to be #y=2x#

Then as instructed in the question: read off the values from the graph:

Intercept for #" "y=2x->(x,y)=(-8/5,-16/5)#

These value would be difficult to read off the graph accurately (precise). This implies that #y-y=2x# could be correct.

Tony B

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