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Solve by factoring : 30x^3 = 21x^2 + 135x  

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schooledmom | Salutatorian

Posted June 6, 2013 at 4:32 PM via web

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Solve by factoring : 30x^3 = 21x^2 + 135x

 

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted June 6, 2013 at 5:07 PM (Answer #1)

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The equation 30x^3 = 21x^2 + 135x has to be solved

30x^3 = 21x^2 + 135x

=> 30x^3 - 21x^2 - 135x = 0

=> x(30x^2 - 21x - 135) = 0

=> 3x(10x^2 - 7x - 45) = 0

=> 3x(10x^2 - 25x + 18x - 45) = 0

=> 3x(5x(2x - 5) + 9(2x - 5)) = 0

=> 3x(5x + 9)(2x - 5) = 0

=> x = 0, x = -9/5 and x = 5/2

The solution of the equation is x = 0, x = -9/5 and x = 5/2

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