Use linear approximation, i.e. the tangent line, to approximate 1.94\displaystyle {1.9}^{{4}} as follows:
Let f(x)=x4\displaystyle {f{{\left({x}\right)}}}={x}^{{4}}. The equation of the tangent line to f(x)\displaystyle {f{{\left({x}\right)}}} at x=2\displaystyle {x}={2} can be written in the form y=mx+b\displaystyle {y}={m}{x}+{b}

where m\displaystyle {m} is:  
and where b\displaystyle {b} is:  


Using this, we find our approximation for 1.94\displaystyle {1.9}^{{4}} is