1-(x/x^2-5+4),(x+1/x^2-16)
2-(6/a6^2-7a+6),(3/a^2-36)
3-(7/x^2+4x+4),(5/4-x^2)
1)$\displaystyle \frac{x}{x^2-5x+4} \ \ , \ \ \frac{x+1}{x^2-16}$
First, factor the denominators:
$\displaystyle (x-1)(x-4) \ \ , \ \ (x-4)(x+4)$
The LCD is found by using all the different factors the most number of times they appear in any one denominator.
$\displaystyle LCD = (x-1)(x-4)(x+4)$
2)$\displaystyle \frac{6}{a^2-7a+6} \ \ , \ \ \frac{3}{a^2-36}$
Same steps as before. Factor the denominators:
$\displaystyle (a-6)(a-1) \ \ , \ \ (a-6)(a+6)$
$\displaystyle LCD = $
Can you finish? Try #3 and see how far you get.