Question 3586
your equation should be written as {{{a=(1/2)b - 4}}} first. What you wrote is misleading.


if a was zero... what value of b is required to give this? Let's find out:


{{{0=(1/2)b - 4}}}
{{{(1/2)b = 4}}}
b = 8


So, since this equation is a straight line (if plotted), see here:


{{{graph(200,200,-4,20,-10,10,y=(1/2)x - 4)}}}


any value of b less than 8 will make a negative.


Jon.