AMC / AIME · Quadratics · Medium

Quadratics: Find math if math has double root math.

Factor and complete square.

Try the problem

Find kk if x2+kx+9x^2+kx+9 has double root x=−3x=-3.

Hint and answer

Concept to use

Discriminant.

Hint

Complete the square or apply the quadratic formula when needed.

Answer

6

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