Question

solve the eq and find value of d D cube - 13D+12=0

Answer 1

$given \: \: {d}^{3} - 13d + 12 = 0 \\ clearly \: 3 \: \: is \: a \: root. \: so \: divide \\ above \: eqn \: with \: (d - 3) \\ we \: get \: {d}^{2} + 3d - 4. \\ (d + 4)(d - 1) = 0 \\ d = 1 \: \: \: \: \: \: - 4 \\ so \: roots \: of \: the \: cubic \: eqn \\ are \: 3 \: \: \: \: 1 \: \: \: - 4$

Answer 2

I hope this helps you