David illustrates how ideas connect to each other in a scientific nonfiction text, using the story of Mexican chemist and Nobel laureate Mario Molina. Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help! Donate or volunteer today! Donate here: https://www.khanacademy.org/donate?utm_source=youtube&utm_medium=desc Volunteer here: https://www.khanacademy.org/contribute?utm_source=youtube&utm_medium=desc Credits: "Air Hockey Saloon" by Chris Zabriskie, licensed under a Creative Commons Attribution License: https://freemusicarchive.org/music/Chris_Zabriskie/Vendaface/05_-_Air_Hockey_Saloon ... https://www.youtube.com/watch?v=NbTeg3Fe_Ys Note: All Khan Academy content is available for free at (www.khanacademy.org)

Solid waste is any discarded material that is not a liquid or gas. It is generated in domestic, industrial, business, and agricultural sectors. Solid waste is most often disposed of in landfills. Landfills can contaminate groundwater and release harmful gases. A sanitary municipal landfill consists of a bottom liner (plastic or clay), a storm water collection system, a leachate collection system, a cap, and a methane collection system. Factors in landfill decomposition include the composition of the trash and conditions needed for microbial decomposition of the waste. Solid waste can also be disposed of through incineration, where waste is burned at high temperatures. This method significantly reduces the volume of solid waste but releases air pollutants. Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help! Donate or volunteer today! Donate here: https://www.khanacademy.org/donate Volunteer here: https://www.khanacademy.org/contribute ... https://www.youtube.com/watch?v=LOzMugtKmN4 Note: All Khan Academy content is available for free at (www.khanacademy.org)

Adding and Subtracting Rational Expressions Watch the next lesson: https://www.khanacademy.org/math/algebra2/polynomial_and_rational/rational_funcs_tutorial/v/adding-and-subtracting-rational-expressions-2?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraII Missed the previous lesson? https://www.khanacademy.org/math/algebra2/polynomial_and_rational/simplifying-rational-expressions/v/simplifying-rational-expressions-3?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraII Algebra II on Khan Academy: Your studies in algebra 1 have built a solid foundation from which you can explore linear equations, inequalities, and functions. In algebra 2 we build upon that foundation and not only extend our knowledge of algebra 1, but slowly become capable of tackling the BIG questions of the universe. We'll again touch on systems of equations, inequalities, and functions...but we'll also address exponential and logarithmic functions, logarithms, imaginary and complex numbers, conic sections, and matrices. Don't let these big words intimidate you. We're on this journey with you! 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=y_DweTAEYWk Note: All Khan Academy content is available for free at (www.khanacademy.org)

Sal works through a few examples showing how to evaluate some common expressions we see involving variables, exponents, and fractions. ... https://www.youtube.com/watch?v=ccyZpjKvJV8 Note: All Khan Academy content is available for free at (www.khanacademy.org)