The key is to bring an x out of the square root: x 2 ( 1 + 3 / x + 2 / x 2 ) = | x | 1 + 3 / x + 2 / x 2 {\displaystyle {\sqrt {x^{2}(1+3/x+2/x^{2})}}=|x|{\sqrt {1+3/x+2/x^{2}}}} .