Question:
Find the limit algebraically:
x→−4limx+4x2−16Answer:
To find the limit of the given expression, we can plug in the value that x is approaching and see what we get. However, when we substitute x=−4 directly into the expression, we encounter an indeterminate form of 00.
Therefore, instead of performing direct substitution, we can use algebraic manipulation in order to simplify the expression and find the limit.
Step 1: Factorize the numerator as the difference of squares:
x2−16=(x+4)(x−4)Step 2: Rewrite the expression:
x+4x2−16=x+4(x+4)(x−4)Step 3: Cancel out the common factor of x+4:
x+4(x+4)(x−4)=x−4Now, we can take the limit as x approaches −4 of the simplified expression:
x→−4limx+4x2−16=x→−4lim(x−4)Since we have eliminated the indeterminate form, we can now plug in x=−4 directly into the expression:
x→−4lim(x−4)=(−4)−4=−8Therefore, the limit of the given expression as x approaches −4 is −8.