Question 312742
{{{f(x)= -(1/2)x-4}}}
a) Substitute -4 for every instance of x and simplify.
{{{f(x)= -(1/2)x-4}}}
{{{f(-4)= -(1/2)(-4)-4}}}
{{{f(-4)= 2-4}}}
{{{highlight_green( f(-4)= -2)}}}
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b)To find the x-intercept, set f(x)=y=0 and solve for x.
{{{f(x)= -(1/2)x-4}}}
{{{ -(1/2)x-4=0}}}
{{{ -(1/2)x=4}}}
{{{highlight_green( x=-8)}}}
(-8,0)
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c)To find the y-intercept, set x=0 and solve for f(x) or y.
{{{f(x)= -(1/2)x-4}}}
{{{f(x)= -(1/2)(0)-4}}}
{{{highlight_green( f(x)= -4)}}}
(0,-4)
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d)The line is in slope-intercept form, {{{y=mx+b}}}, where m is the slope.
{{{highlight_green( m=-1/2)}}}
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e)Perpendicular lines have slopes that are negative reciprocals of each other.
{{{m1*m2=-1}}}
{{{-(1/2)*m2=-1}}}
{{{m2=2}}}
A line perpendicular to the given line will have a slope of {{{highlight_green( m=2)}}}. 
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Here's a graph of the original line and a perpendicular line {{{y=2x}}}.
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{{{ drawing( 300, 300, -10, 10, -10, 10, circle(0,-4,.45),circle(-8,0,.45), graph( 300, 300, -10, 10, -10, 10, -(1/2)x-4, 2x)) }}}
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The given line is in red (Note the x and y intercepts)
The perpendicular line is in green.