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  • Solving quadratic equations | Lesson (article) | Khan Academy
    Quadratic equations without x -terms such as 2 x 2 = 32 can be solved without setting a quadratic expression equal to 0 Instead, we can isolate x 2 and use the square root operation to solve for x When solving quadratic equations by taking square roots, both the positive and negative square roots are solutions to the equation
  • The quadratic formula | Algebra (video) | Khan Academy
    The quadratic formula helps us solve any quadratic equation First, we bring the equation to the form ax²+bx+c=0, where a, b, and c are coefficients Then, we plug these coefficients in the formula: (-b±√ (b²-4ac)) (2a) See examples of using the formula to solve a variety of equations Created by Sal Khan
  • Completing the square review (article) | Khan Academy
    Completing the square is a technique for factoring quadratics This article reviews the technique with examples and even lets you practice the technique yourself
  • Solving simple quadratics review (article) | Khan Academy
    Simple quadratic equations like x^2=4 can be solved by taking the square root This article reviews several examples and gives you a chance to practice on your own
  • Solving quadratics by completing the square: no solution
    Sal solves the equation 4x^2+40x+280=0 by completing the square, only to find there's no solution for this equation
  • Completing the square (video) | Khan Academy
    Some quadratic expressions can be factored as perfect squares For example, x²+6x+9=(x+3)² However, even if an expression isn't a perfect square, we can turn it into one by adding a constant number For example, x²+6x+5 isn't a perfect square, but if we add 4 we get (x+3)² This, in essence, is the method of *completing the square*
  • Solve quadratic equations: complex solutions - Khan Academy
    Solve quadratic equations using the quadratic formula Some of the equations have real solutions while others have complex solutions
  • Linear and quadratic systems | Lesson (article) | Khan Academy
    Solving linear and quadratic systems algebraically Our goal when solving a system of equations is to reduce two equations with two variables down to a single equation with one variable Since each equation in the system has two variables, one way to reduce the number of variables in an equation is to substitute an expression for a variable





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