Consider the differential equation $y^{\text{'}\text{'}}-2x{y}^{\text{'}}y=0$ subject to $y(0)=1$ and $y^{\text{'}}(0)=5.$

The first few terms of the power series solution $y={\displaystyle \underset{n=0}{\overset{}{}}}{a}_k{x}^k$ are

$y$~~$15x-\frac{1}{2}{x}^2\frac{1}{6}{x}^3$

Use this to approximate $y(x)$ at $x=\mathrm{.}2$

Round your answer to $2$ decimal places.