does the equation below define a liner function
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This function is a hyperbola. It graphs out two disjoint curves. A linear function produces a single straight line graph. All linear functions can be written in the form y = mx+b. The x being in the denominator is one indicator we cannot write the original equation in the form y = mx+b.
y = 3/x is the same as xy = 3; this tells us every point on y = 3/x has its (x,y) coordinate pair multiply to 3.