A-REI.4.b

Solve quadratic equations by inspection (e.g., for x^2 = 49), taking square roots, completing the square, the quadratic formula and factoring, as appropriate to the initial form of the equation. Recognize when the quadratic formula gives complex solutions.

Khan Academy Resources

Understanding the quadratic formulaSolving quadratics by completing the squareSolving quadratics by factoring reviewQuadratic formula proof reviewCompleting the square reviewSolving simple quadratics reviewSquare roots of perfect squaresDiscriminant reviewSolving quadratics by taking square roots Quadratic formula reviewCube roots reviewSolving quadratics by factoringQuadratic formulaQuadratics by factoring (intro)Completing the square (intermediate)Completing the squareQuadratics by factoringQuadratics by taking square rootsCube rootsSquare rootsQuadratic word problems (standard form)Solve equations by completing the squareSquare and cube challengeSolve equations using structureEquations with square roots & cube rootsCompleting the square (intro)Quadratics by taking square roots (intro)Equations with square roots: decimals & fractionsSolve quadratic equations: complex solutionsRoots of decimals & fractionsQuadratics by taking square roots: with stepsQuadratics by taking square roots: strategyZero product propertyStrategy in solving quadraticsQuadratic word problem: ballWorked example: completing the square (leading coefficient ≠ 1)Worked example: quadratic formula (negative coefficients)Solving quadratics by taking square rootsSolving quadratic equations: complex rootsCompleting the squareThe quadratic formulaSolving quadratics by factoringSolving quadratics by completing the square: no solutionWorked example: quadratic formula (example 2)Using the quadratic formula: number of solutionsSolve by completing the square: Non-integer solutionsSolving quadratics using structureSquare root of decimalSolve by completing the square: Integer solutionsZero product propertyIntro to cube rootsStrategy in solving quadratic equationsSolving quadratics by taking square roots examplesSolving quadratics by taking square roots: with stepsSolving quadratics by factoring: leading coefficient ≠ 1Intro to square rootsDimensions of a cube from its volumeWorked example: Rewriting & solving equations by completing the squareQuadratics by taking square roots: strategyWorked example: Rewriting expressions by completing the square

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