Question

If alpha and beta are the zeros of the quadratic polynomial p(x)=x^2-5x+6, then find the value of alpha+beta-3alpha beta

Answer 1

$we \: know \: that \\ \alpha + \beta = 5 \\ and \: \: \: \alpha \beta = 6 \\ so \: \: \\ (\alpha + \beta) - 3 (\alpha \beta ) = 5 - 3(6) \\ = > 5 - 18 \\ = > - 13$