Với `x \ne 0,x \ne +-2,x \ne 1`. Ta có:
`C=([x+2]/[2-x]+[4x^2]/[4-x^2]-[2-x]/[x+2]):[x^2-x]/[2x-x^2]`
`C=[(x+2)^2+4x^2-(2-x)^2]/[(2-x)(2+x)].[x(2-x)]/[x(x-1)]`
`C=[(x+2-2+x)(x+2+2-x)+4x^2]/[2+x]. 1/[x-1]`
`C=[2x.4+4x^2]/[(2+x)(x-1)]`
`C=[4x(2+x)]/[(2+x)(x-1)]=[4x]/[x-1]`