A linear approximation of {{MATH_65}} is a ``good'' approximation as long as {{MATH_66}} is ``not too far'' from {{MATH_67}}. {{COMMENT_68}} If one ``zooms in'' on the graph of {{MATH_69}} sufficiently, then the graphs of {{MATH_70}} and {{MATH_71}} are nearly indistinguishable. As a first example, we will see how linear approximations allow us to approximate ``difficult'' computations.