One root of the quadratic equation X 2 12x a 0 is twice the other Find the value of a ...........

Quantitative Aptitude (CDS) Quadratic Equations

One root of the quadratic equation. X^2-12x+a= 0 is twice the other. Find the value of a?

Let the roots of the quadratic equation be X and 3X.
Sum of roots=-(-12)=12
X+3X=12
4X=12
X=3
Product of the roots=a
X×3X=a
3X^2=a
3×3^2=a
a=27

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