Roots That Are Not Whole
Part of the Factoring & Quadratics section of Coddy's Algebra journey. Lesson 46 of 63.
x^2 = 5: no whole number squares to 5, but the equation still has two solutions. They are written with the radical sign: x = ±√5, the exact numbers whose squares are 5.
√5 is not a made-up dodge; it is a number a little over 2.2, living between √4 = 2 and √9 = 3. Exact answers keep the radical; a calculator can approximate it whenever a decimal is wanted.
So the root method never fails on x^2 = positive number: perfect squares give whole answers, the rest give radicals, and both are complete, correct solutions. What happens with a NEGATIVE number on the right is a different story, told two chapters from now.
Challenge
EasySolve x^2 = 13 exactly.
Try it yourself
Solve for x
This lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Factoring & Quadratics
1What Factoring Is
Two DirectionsThe Reverse GearUn-Distributing LettersThe Check Is MultiplicationRecap: First Factors4Minus Signs in the Machine
A Negative ProductWhich One Gets the MinusBoth NegativeThe Sign MapRecap: Signs2The Greatest Common Factor
Number and Letter TogetherThe Largest OneHigher PowersThree Terms Share TooRecap: The GCF5Special Shapes
A Missing MiddleThe Shape in LettersThe Perfect SquareThe Minus VersionPrime PolynomialsRecap: Special Shapes3The Sum-Product Machine
Reading the ProductHunting the PairThe Machine in LettersLonger HuntsRecap: The Machine6Factor Completely
Two LayersSquares InsideCompletely Means CompletelyThe Deep CheckRecap: Factor Completely9The Square Root Method
Undoing a SquareArrange, Then RootA Squared PackageRoots That Are Not WholeRecap: Square Roots