`a,` `P=({2x}/{x^3+x^2+x+1}+x/{x+1}):(1+x/{x+1})`
`⇔P=({2x}/{(x^2+1)(x+1)}+{x(x^2+1)}/{(x^2+1)(x+1)}):{2x+1}/{x+1}`
`⇔P=({2x}/{(x^2+1)(x+1)}+{x^3+x}/{(x^2+1)(x+1)}):{2x+1}/{x+1}`
`⇔P={3x+x^3}/{(x^2+1)(x+1)}.{x+1}/{2x+1}`
`⇔P={3x+x^3}/{(x^2+1)(2x+1)}`
`b,` `x=1/4⇔P={3. 1/4+(1/4)^3}/{((1/4)^2+1)(2. 1/4+1)}`
`⇔P={3/4+1/64}/{(1/16+1)(2/4+1)}`
`⇔P={49/64}/{17/16. 6/4}`
`⇔P=49/64:51/16`
`⇔P=49/204`
`c,` `1/P={(x^2+1)(2x+1)}/{3x+x^3}`
