Substitute x=1: To find the limit of the given function as x approaches 1, we first substitute x=1 into the function to see if it results in an indeterminate form.limx→15x−1−2x−1=5⋅1−1−21−1=5−1−20=2−20=00Since we get 0/0, which is an indeterminate form, we need to use algebraic manipulation to simplify the expression and resolve the indeterminate form.
Multiply by conjugate: To eliminate the square root in the denominator, we can multiply the numerator and the denominator by the conjugate of the denominator. The conjugate of 5x−1−2 is 5x−1+2.limx→15x−1−2x−1⋅5x−1+25x−1+2=(5x−1−2)(5x−1+2)(x−1)(5x−1+2)
Simplify denominator: Now we simplify the denominator using the difference of squares formula: (a−b)(a+b)=a2−b2. The denominator becomes (5x−1)2−(2)2=(5x−1)−4=5x−5.
Expand numerator: The numerator is expanded by distributing x−1 to both terms in the conjugate 5x−1+2. The numerator becomes x(5x−1)+2x−5x−1−2.
Factor out common terms: Now we have the following limit: limx→1[x(5x−1)+2x−5x−1−2]/(5x−5) We can simplify this by factoring out common terms and canceling them out.
Cancel out common factor: We notice that the numerator and denominator both have terms that can be factored by x−1. The numerator can be rewritten as (x−1)(5x−1+2) and the denominator as 5(x−1). Now we have: x→1lim5(x−1)(x−1)(5x−1+2)
Simplify expression: Since (x−1) is a common factor in both the numerator and the denominator, we can cancel it out, leaving us with: x→1lim(5x−1+2)/5
Substitute x=1: Now we can substitute x=1 into the simplified expression without getting an indeterminate form: x→1lim(55x−1+2)=(55⋅1−1+2)=(55−1+2)=(54+2)=(52+2)=54
Final result: The limit as x approaches 1 of the given function is 54, which corresponds to answer choice (B).
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