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Lösung 2.3:2d

Aus Online Mathematik Brückenkurs 1

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The equation can be written in normalized form (i.e. the coefficient in front of x2 is 1 ) by dividing both sides by 4,


x27x+413=0


Completing the square on the left-hand side,


x27x+413=x272272+413=x272449+413=x272436=x2729

The equation can therefore be written as


x2729=0 

and taking the square root gives the solutions as


x27=9=3  i.e. x=27+3=213


x27=9=3  i.e. x=273=21


As an extra check, we substitute x=1/2 and x=13/2 into the equation:


x=12: LHS =42122821+13=44114+13=114+13=  RHS

x=132: LHS =4213228213+13=441691413+13=169182+13=  RHS