Q. Evaluate the following limit using L'Hospital's rule.x→0+lim(9x)sin(5x)
Recognize Indeterminate Form: First, recognize that the limit is of the form 00, which is indeterminate. We can use L'Hospital's Rule by taking the natural log of the function and then exponentiating the result at the end.
Take Natural Log: Let's set y=(9x)(sin(5x)) and take the natural log of both sides to get ln(y)=sin(5x)⋅ln(9x).
Find Limit of ln(y): Now we find the limit of ln(y) as x approaches 0 from the positive side. We have limx→0+(sin(5x)⋅ln(9x)).
Apply L'Hospital's Rule: We can apply L'Hospital's Rule to this limit since it's in the indeterminate form 0⋅(−∞). Differentiate the numerator and denominator with respect to x.
Differentiate Numerator and Denominator: The derivative of sin(5x) with respect to x is 5cos(5x), and the derivative of ln(9x) with respect to x is x1.
Simplify the Limit: Now we have limx→0+(1/x5cos(5x)). This simplifies to limx→0+(5x⋅cos(5x)).
Evaluate Limit: As x approaches 0, 5x approaches 0 and cos(5x) approaches 1. So the limit of 5x⋅cos(5x) as x approaches 0 is 0.
Exponentiate to Find Limit of y: Since we took the natural log earlier, we need to exponentiate to get the limit of y. So, e0=1.
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