Use linear approximation, i.e. the tangent line, to approximate 3125.4125.43 as follows: Let f(x)=3xf(x)=x3. The equation of the tangent line to f(x)f(x) at x=125x=125 can be written in the form y=mx+by=mx+b where mm is: and where bb is: Using this, we find our approximation for 3125.4125.43 is