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Thank you for your response, Mark44. Could you please explain the red box?

Hello everyone, I'm posting here since I'm only having trouble with an intermediate step in proving that \sqrt{x} \text{ is uniformly continuous on } [0, \infty] . By definition, |x - x_0| < ε^2 \Longleftrightarrow -ε^2 < x - x_0 < ε^2 \Longleftrightarrow -ε^2 + x_0 < x < ε^2 + x_0 1...

Thank you for your responses, Bohrok and HallsofIvy. @HallsofIvy: Thanks for your clarification on conjugates. How would you define a real conjugate then? Are two terms x and y conjugates of each other if and only x \times y are of degree 1 and do not have any fractional exponents?

Homework Statement Evaluate the limit, WITHOUT using l'Hôpital's rule: \lim_{x \rightarrow -1} \frac{x^{1/3} + 1}{x^{1/5} + 1} Homework Equations The Attempt at a Solution I tried to use the conjugate method which does not produce a useful outcome: \underset{x\to...

Thank you very much for your replies, Tedjn and Bohrok. I was able to evaluate this limit.

Homework Statement [B]Evaluate \underset{x\to 0}{\mathop{\lim }}\,\frac{\sec \frac{x}{2}-1}{x\sin x} , WITHOUT using l'Hôpital's rule. Homework Equations The Attempt at a Solution Hello there, I tried to evaluate this limit using two different approaches, both of which still...

Adminstrator: This is a double post, so please feel free to delete this one. The relevant post is "Limit of a Trigonometric Function (Involved Problem)". Homework Statement Evaluate \underset{x\to 0}{\mathop{\lim }}\,\frac{\sec \frac{x}{2}-1}{x\sin x} Homework Equations The Attempt at...

Hi Bohrok, I'm just evaluating this limit for fun. Could you please reveal the last substitution which you made to get \frac{\sin x}{x} ? Thanks.

Thanks for your response, Hurkyl. Proof that \lim_{x \rightarrow 0} \frac{1}{x} does not exist: \lim_{x \rightarrow 0^{-}} \frac{1}{x} = \frac{1}{0^{-}} = -\infty \lim_{x \rightarrow 0^{+}} \frac{1}{x} = \frac{1}{0^{+}} = \infty Since the right- and left-sided limits differ and...

Thank you for your response, Hurkyl. However, how would I show with an assumed delta value that the above limit does not exist?

Hello there, I would like to learn how I can use the formal definition of a limit to prove that a limit does not exist. Unfortunately, my textbook (by Salas) does not offer any worked examples involving the following type of limit so I am not sure what to do. I write below that delta = 1 would...

Thanks for your reply, Dick. I have: \vec{u} = |\vec{u}| \cos A1 \hat{i} + |\vec{u}| \cos B1 \hat{j} + |\vec{u}| \cos Y1 \hat{k} \vec{v} = |\vec{v}| \cos A2 \hat{i} + |\vec{v}| \cos B2 \hat{j} + |\vec{v}| \cos Y2 \hat{k} If I dot these two expressions on the RS, I do not see...

Could anyone please offer an explanation for how to prove the above? Thank you!

Thank you for your response. Would you mind elaborating on the proof? I thought that the direction cosines themselves were the unit vectors, so how would \cos A1 \cos A2 = 0 ? Shouldn't the dot product of these direction cosines = 0?

Hello everyone, Thank you in advance for your help! --- Homework Statement 10. A vector \vec{u} with direction angles A1, B1, and Y1, is perpendicular to a vector \vec{v} with direction angles A2, B2, and Y2. Prove that: \cos A1 \cos B2 + \cos B1 \cos B2 + \cos Y1 \cos Y2 = 0. ---...

Hello there: Here is my solution, which matches your textbook's. y = \cos(a^3 + x^3) Let: u = a^3 + x^3 The Chain Rule: h'(x) = f'(g(x)) \times g'(x) Breaking the original equation down: f(x) = \cos u , f'(x) = -\sin u g(x) = u = a^3 + x^3 , g'(x) = 3x^2 (From the Product Rule)...