Problem to solve
Compute \[ \lim_{ x \to 4^- } \frac{3}{x-4} \]
Solution
STEP 1
Find the following limit:
lim_(x->4^-) 3/(x - 4)
STEP 2
Hint: | If neither of the terms of a product approach 0 as x->a, then by the product rule, the limit of the product is the product of the limits.
Applying the product rule, write lim_(x->4^-) 3/(x - 4) as 3 lim_(x->4^-) 1/(x - 4):
3 lim_(x->4^-) 1/(x - 4)
STEP 3
Hint: | If lim_(x->4^-) y = 0, then the limit of 1/y is ± ∞.
Since lim_(x->4^-)(x - 4) = 0 and x - 4<0 for all x just to the left of x = 4, lim_(x->4^-) 1/(x - 4) = -∞:
3 -∞
STEP 4
Hint: | Evaluate 3 (-∞).
3 (-∞) = -∞:
Answer: | 
 | -∞