Sal finds the first and the second derivatives of the vector-valued function h(t)=(-t_-6,4t_+2t+1). Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/ap-calculus-bc/bc-derivatives-advanced/bc-diff-param-vec-func/e/second-derivatives--vector-valued-functions-?utm_source=YT&utm_medium=Desc&utm_campaign=APCalculusBC Watch the next lesson: https://www.khanacademy.org/math/ap-calculus-bc/bc-derivatives-advanced/bc-polar-functions-differentiation/v/derivatives-in-polar-coordinates?utm_source=YT&utm_medium=Desc&utm_campaign=APCalculusBC Missed the previous lesson? https://www.khanacademy.org/math/ap-calculus-bc/bc-derivatives-advanced/bc-diff-param-vec-func/v/second-derivative-of-parametric-functions?utm_source=YT&utm_medium=Desc&utm_campaign=APCalculusBC AP Calculus BC on Khan Academy: Learn AP Calculus BC - everything from AP Calculus AB plus a few extra goodies, such as Taylor series, to prepare you for the AP Test ... https://www.youtube.com/watch?v=-vv63FS__bY Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction to PCR (polymerase chain reaction). Watch the next lesson: https://www.khanacademy.org/test-prep/mcat/biomolecules/dna-technology/v/dna-libraries-generating-cdna?utm_source=YT&utm_medium=Desc&utm_campaign=mcat Missed the previous lesson? https://www.khanacademy.org/test-prep/mcat/biomolecules/dna-technology/v/gel-electrophoresis-dna?utm_source=YT&utm_medium=Desc&utm_campaign=mcat MCAT on Khan Academy: Go ahead and practice some passage-based questions! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. ... https://www.youtube.com/watch?v=nHi-3jP6Mvc Note: All Khan Academy content is available for free at (www.khanacademy.org)

We want you to feel comfortable moving between seconds, minutes, and hours. Let's create some tables where we compare and covert these measurements of time. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-unit-conversion/e/measurement-units?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Watch the next lesson: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-unit-conversion/v/feet-to-inches-exercise-example?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-measurement-topic/cc-4th-unit-sense/v/unit-sense-exercise-example-2?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Grade 4th on Khan Academy: 4th grade is the time to start really fine-tuning your arithmetic skills. Not only will you be a multi-digit addition and subtraction rockstar, but you'll extend the multiplication and division that you started in 3rd grade to several digits. You'll also discover that you sometimes have something left over (called a "remainder") when you divide. In 3rd grade you learned what a fraction is. Now you'll start adding, subtracting, multiplying, and comparing them. You'll also see how they relate to decimals. On other fronts, you'll learn how to convert between different units (which is super important when comparing the size and speed of robot unicorns in different countries) and continue your journey thinking about various shapes in two dimensions. Some of the foundational concepts of geometry (like lines, rays and angles) also get introduced. As always, we'll round this out with a healthy dose of applied word problems and explorations of number patterns and properties (including the ideas of factors, multiples and prime numbers). The fun must not stop! (Content was selected for this grade level based on a typical curriculum in the United States.) ... https://www.youtube.com/watch?v=-r7JwuSdj5M Note: All Khan Academy content is available for free at (www.khanacademy.org)

Introduction to complex numbers. Adding, subtracting and multiplying complex numbers. ... https://www.youtube.com/watch?v=kpywdu1afas Note: All Khan Academy content is available for free at (www.khanacademy.org)