The line should be:
x p ( t ) = c 1 e t . {\displaystyle x_{p}(t)=c_{1}e^{t}.} Then x ˙ p ( t ) = c 1 e t , {\displaystyle {\dot {x}}_{p}(t)=c_{1}e^{t},} and substituting gives
Return to errata.
