What is the value of k so that the two roots of equation x² - kx + 36 = 0 are equal?

For a quadratic equation to have equal roots, its discriminant must equal zero according to the discriminant formula, so b squared minus 4 a c equals 0. Substituting the values from the equation gives (-k) squared minus 4 times 1 times 36 equals 0. Simplifying this yields k squared equals 144, meaning k equals 12 or -12, so the positive value is 12.

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