Explanation
Step 1: Divide numerator and denominator by x2
Divide each term individually:
L=x→∞limx22x2+x23xx25x2+x27
Simplify the terms inside the expression:
L=x→∞lim2+x35+x27
Step 2: Apply the limit x→∞
As x grows infinitely large (x→∞), any fraction with a constant numerator and x in the denominator approaches 0:
limx→∞x27=0
limx→∞x3=0
Substituting these values into our expression gives:
L=2+05+0
L=25
Shortcut Rule for Rational Limits at Infinity:
When evaluating limx→∞Q(x)P(x) where the degree of the numerator polynomial equals the degree of the denominator polynomial, the limit is simply the ratio of their leading coefficients.
Here, the leading coefficient of the numerator is 5 and the denominator is 2. Therefore, the answer is directly 25.
Correct Answer:
(a) 5/2