$[12]$ Plot and Find the stationary points of each of the corresponding functions within the range $-10x10.$ Classify the type of each stationary point $($Minimum$,$ Maximum, or Inflection$).$

a$)y=x^2+2x$

b$)y=1\mathrm{.}5x^3-x-5$

c$)y=x^4-x^2+1$

d$)y=x^2+2cos(0\mathrm{.}1x)$