Question:
Evaluate the following limit algebraically:
x→2limx2−4xx3−8Answer:
To find the limit, we can't simply substitute x=2 into the expression, because it would result in an indeterminate form of 00. Instead, we need to manipulate the expression algebraically to simplify it before taking the limit.
Let's factor the numerator and denominator of the expression:
x→2limx2−4xx3−8=x→2limx(x−4)(x−2)(x2+2x+4)Now, we can cancel out the common factor of (x−2) in the numerator and denominator:
x→2limx(x−4)(x−2)(x2+2x+4)=x→2limx−4x2+2x+4Since the denominator still evaluates to zero at x=2, we need to simplify further. Notice that the numerator of the expression can be factored as well:
x→2limx−4x2+2x+4=x→2limx−4(x−2)(x+2)+8Now, we can cancel out the factor of (x−2):
x→2limx−4(x−2)(x+2)+8=x→2limx−4x+2+8Finally, we can substitute x=2 into the simplified expression:
x→2limx−4x+2+8=2−42+2+8=−212=−6Therefore, the limit of the given expression, as x approaches 2, is equal to −6.