Olfactory neurons ... https://www.youtube.com/watch?v=BT2ZPUPyL5g Note: All Khan Academy content is available for free at (www.khanacademy.org)

In this worked example, Sal finds the area of the image of a rectangle after a transformation defined by a given matrix. This is done by finding the area of the pre-image and multiplying by the matrix's determinant. ... https://www.youtube.com/watch?v=aVuCoUxt3vc Note: All Khan Academy content is available for free at (www.khanacademy.org)

Learn how to evaluate an expression with variables using a technique called substitution (or "plugging in"). Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-algebra/variable-and-expressions/v/evaluate-a-formula-using-substitution?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraI Missed the previous lesson? https://www.khanacademy.org/math/algebra/introduction-to-algebra/variable-and-expressions/v/why-aren-t-we-using-the-multiplication-sign?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraI Algebra I on Khan Academy: Algebra is the language through which we describe patterns. Think of it as a shorthand, of sorts. As opposed to having to do something over and over again, algebra gives you a simple way to express that repetitive process. It's also seen as a "gatekeeper" subject. Once you achieve an understanding of algebra, the higher-level math subjects become accessible to you. Without it, it's impossible to move forward. It's used by people with lots of different jobs, like carpentry, engineering, and fashion design. In these tutorials, we'll cover a lot of ground. Some of the topics include linear equations, linear inequalities, linear functions, systems of equations, factoring expressions, quadratic expressions, exponents, functions, and ratios. 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=AJNDeVt9UOo Note: All Khan Academy content is available for free at (www.khanacademy.org)

Molecular solids ... https://www.youtube.com/watch?v=9Xr2LNSPKFA Note: All Khan Academy content is available for free at (www.khanacademy.org)