Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/precalculus/vectors-precalc/rect-form/e/adding_vectors?utm_source=YT&utm_medium=Desc&utm_campaign=Precalculus Watch the next lesson: https://www.khanacademy.org/math/precalculus/vectors-precalc/rect-form/v/vector-components-from-initial-and-terminal-points?utm_source=YT&utm_medium=Desc&utm_campaign=Precalculus Missed the previous lesson? https://www.khanacademy.org/math/precalculus/vectors-precalc/rect-form/v/intro-unit-vector-notation?utm_source=YT&utm_medium=Desc&utm_campaign=Precalculus Precalculus on Khan Academy: You may think that precalculus is simply the course you take before calculus. You would be right, of course, but that definition doesn't mean anything unless you have some knowledge of what calculus is. Let's keep it simple, shall we? Calculus is a conceptual framework which provides systematic techniques for solving problems. These problems are appropriately applicable to analytic geometry and algebra. Therefore....precalculus gives you the background for the mathematical concepts, problems, issues and techniques that appear in calculus, including trigonometry, functions, complex numbers, vectors, matrices, and others. There you have it ladies and gentlemen....an introduction to precalculus! ... https://www.youtube.com/watch?v=-2HwisGonfc Note: All Khan Academy content is available for free at (www.khanacademy.org)

Evaluate 3x^2-8x+7 when x=-2 Watch the next lesson: https://www.khanacademy.org/math/algebra/introduction-to-polynomials-and-factorization/introduction-to-polynomials/v/polynomials1?utm_source=YT&utm_medium=Desc&utm_campaign=AlgebraI Missed the previous lesson? https://www.khanacademy.org/math/algebra/introduction-to-polynomials-and-factorization/introduction-to-polynomials/v/terms-coefficients-and-exponents-in-a-polynomial?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=03yq7XsErqo Note: All Khan Academy content is available for free at (www.khanacademy.org)

Learn how to write basic expressions with variables to describe situations described in word problems. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-expressions-and-variables/cc-6th-alg-expression-word-problems/e/writing-expressions-with-variables-word-problems?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Watch the next lesson: https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-expressions-and-variables/cc-6th-alg-expression-word-problems/v/more-fancy-expressions-from-word-problems?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-expressions-and-variables/cc-6th-writing-expressions/v/writing-expressions-2?utm_source=YT&utm_medium=Desc&utm_campaign=6thgrade Grade 6th on Khan Academy: By the 6th grade, you're becoming a sophisticated mathemagician. You'll be able to add, subtract, multiply, and divide any non-negative numbers (including decimals and fractions) that any grumpy ogre throws at you. Mind-blowing ideas like exponents (you saw these briefly in the 5th grade), ratios, percents, negative numbers, and variable expressions will start being in your comfort zone. Most importantly, the algebraic side of mathematics is a whole new kind of fun! And if that is not enough, we are going to continue with our understanding of ideas like the coordinate plane (from 5th grade) and area while beginning to derive meaning from data! (Content was selected for this grade level based on a typical curriculum in the United States.) ... https://www.youtube.com/watch?v=lq-2gX3NKCM Note: All Khan Academy content is available for free at (www.khanacademy.org)

Finding the proportion of a normal distribution that is below a value by calculating a z-score and using a z-table. View more lessons or practice this subject at http://www.khanacademy.org/math/ap-statistics/density-curves-normal-distribution-ap/normal-distributions-calculations/v/z-table-for-proportion-below?utm_source=youtube&utm_medium=desc&utm_campaign=apstatistics AP Statistics on Khan Academy: Meet one of our writers for AP¨_ Statistics, Jeff. A former high school teacher for 10 years in Kalamazoo, Michigan, Jeff taught Algebra 1, Geometry, Algebra 2, Introductory Statistics, and AP¨_ Statistics. Today he's hard at work creating new exercises and articles for AP¨_ Statistics. 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 ... https://www.youtube.com/watch?v=Fo4kitkFB3I Note: All Khan Academy content is available for free at (www.khanacademy.org)