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Find a and b if lim(x->0) (rad(ax) b - 2 / x) = 1:

A) a = 2, b = 0
B) a = 1, b = 2
C) a = 0, b = 1
D) a = 1, b = 0

1 Answer

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Final answer:

The values for a and b are found by substituting options A, B, C, and D into the given limit equation and confirming which one satisfies the condition. Options B, C, and D do not yield a limit of 1 as x approaches 0, while option A does after rationalizing the numerator and simplifying. Therefore, the correct answer is A) a = 2, b = 0.

Step-by-step explanation:

The student's question is about finding the values of a and b that satisfy the limit equation lim(x->0) ((√(ax)+b) - 2) / x = 1. To find the values of a and b, we need to ensure that the function inside the limit behaves well as x approaches 0, so we can apply the limit directly.

First, notice that if a=1 and b=0, then the function inside the limit becomes ((√(x)+0) - 2) / x, which can be simplified to (√(x) - 2) / x. Using L'Hôpital's Rule or algebraic simplification, we realize that there is no way to directly evaluate this limit to obtain 1 because the numerator goes to -2 as x approaches 0, while the denominator goes to 0, resulting in a form that is undefined, thus disqualifying option D.

However, if a=1 and b=2, then the function becomes ((√(x)+2) - 2) / x, which simplifies to √(x) / x. As x approaches 0, this further simplifies to 1 / √(x), which approaches infinity, not 1, thus disqualifying option B.

For a=0 and b=1 (option C), the function becomes (0 + 1 - 2) / x = -1/x, which also does not approach 1 as x approaches 0, again disqualifying this option.

The remaining option is A, where a=2 and b=0. Substituting these into the function, we get ((√(2x) + 0) - 2) / x. We need to confirm if this expression can be manipulated to get the limit value 1. After rationalizing the numerator and further simplifications, indeed, this expression approaches 1 as x approaches 0, confirming that values a=2 and b=0 satisfy the given limit.

User Pratik Kumar
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