Question

Lim x-1 x³-2x²+3x-2/(2x^4-3x+1)

Answer 1

Since the limit becomes the undetermined form

$\displaystyle \lim_{x\to 1} \dfrac{x^3-2x^2+3x-2}{2x^4-3x+1} \to \dfrac{0}{0}$

it means that both polynomials have a root at $x=1$. So, we can fact both numerator and denominator:

$x^3-2x^2+3x-2 = (x-1)(x^2-x+2)$

$2x^4-3x+1 = (x-1)(2x^3+2x^2+2x-1)$

So, the fraction becomes

$\dfrac{(x-1)(x^2-x+2)}{(x-1)(2x^3+2x^2+2x-1)} = \dfrac{x^2-x+2}{2x^3+2x^2+2x-1}$

Now, as x approaches 1, you have no problems anymore:

$\displaystyle \lim_{x\to 1} \dfrac{x^2-x+2}{2x^3+2x^2+2x-1} \to \dfrac{2}{5}$