Sunday, 6 July 2014

algebra precalculus - exponential equation



(5+26)x+(526)x=10




So I have squared both sides and got:



(526)x+(5+26)x+21x=100



(526)x+(5+26)x+2=100



I don't know what to do now


Answer



You don't have to square the equation in the first place.




Let y=(5+26)x, then 1y=(526)x. Hence you have y+1y=10 i.e. y2+1=10y i.e. y210y+1=0.



Hence, (y5)2=24y=5±26.



Hence, (5+26)x=5±26x=±2



(If you plug in x=±2, you will get 5+26+526 which is nothing but 10)


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