Question

if the equation x³ + ax² + bx - 4 = 0 has two roots equal to 2 , then the ordered pair (a,b) is

Answer 1

$$\begin{gathered} \mathrm{Dear}\mathrm{Student}, \\ \mathrm{Let}\mathrm{the}\mathrm{third}\mathrm{root}\mathrm{is}\mathrm{x}\mathrm{so} \\ \mathrm{So}2+2+\mathrm{x}=-\frac{\mathrm{a}}{1}=-\mathrm{a} \\ 2\times 2+2\times \mathrm{x}+\mathrm{x}\times 2=\mathrm{b} \\ \mathrm{and} \\ 2\times 2\times \mathrm{x}=4 \\ \mathrm{So}\mathrm{x}=1 \\ \mathrm{and}\mathrm{hence}\mathrm{a}=-4 \\ \mathrm{and}\mathrm{b}=8 \\ \mathrm{Regards} \end{gathered}$$