Question

Factor the Expression. If the expression cannot be factored, say so. 10.) c^2 - 9c - 18

Answer 1

$C^2-9C-18$

we can match 0 and find the roots

$C^2-9C-18=0$

ussing...

$C=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}$

where a=1, b=-9 and c=-18

so replacing

$\begin{gathered} C=\frac{-(-9)\pm\sqrt[]{(-9)^2-4(1)(-18)}}{2(1)} \\ \\ C=\frac{9\pm\sqrt[]{81+72}}{2} \\ \\ C=\frac{9\pm3\sqrt[]{17}}{2} \end{gathered}$

we have 2 roots

$\begin{gathered} C_1=\frac{9+3\sqrt[]{17}}{2} \\ \\ C_2=\frac{9-3\sqrt[]{17}}{2} \end{gathered}$

now the factoring is

$(C-\frac{9-3\sqrt[]{17}}{2})(C-\frac{9+3\sqrt[]{17}}{2})=0$