Science and Mathematics for Engineering 6th Edition by John Bird

Exercise 20

Plot a graph of $y = \frac { 1 } { 2 } e ^ { - 1.2 x }$ over the range $x = - 2$ to $x = + 1$ and hence determine, correct to 1 decimal place, (a) the value of $y$ when $x = - 0.75$ , and $( b )$ the value of $x$ when $y = 4.0$