Bring terms together: First, we need to bring all terms to one side of the equation to set it equal to 0.4x3+72x2+324x=0
Factor out common factor: Next, we can factor out the greatest common factor, which is 4x in this case.4x(x2+18x+81)=0
Factor quadratic equation: Now, we need to factor the quadratic equation if possible. x2+18x+81 is a perfect square trinomial, which factors into (x+9)2. 4x(x+9)2=0
Set factors equal to zero: We can now set each factor equal to zero to find the roots of the equation.First, set 4x to zero:4x=0x=0
Find roots: Then, set (x+9)2 to zero:(x+9)2=0x+9=0x=−9
Identify repeated root: Since (x+9)2 is a square, it gives us the same root twice, so x=−9 is a repeated root.Therefore, the roots of the equation are x=0 and x=−9 (with a multiplicity of 2).
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