[tex]\text{The answer is c}^{11}[/tex]
explanation/ Working:
[tex]c^2.c^9=c^2\times c^9=c^{2+9}=c^{11}[/tex]
Rule on iindex says when the base is same, you should add the powers
[tex]c^2.c^9=\text{ (c}\times c)\times(c\times c\times c\times c\times c\times c\times c\times c\times c)=c^{11}[/tex]
