Practise a differential relation and a logarithm of secant

(a) It is given that $dy/dx=y+2x$ and that y=1 when x=0. Find the first three terms in the Maclaurin series for y.

(b) Show that the Maclaurin series for $\ln(\sec x)$, up to and including the term in $x^4$, is $\tfrac12x^2+\tfrac1{12}x^4$.