Let f(x)={7x+9ifx<87ifx=821x+5ifx>8\displaystyle {f{{\left({x}\right)}}}={\left\lbrace\begin{array}{ccc} \frac{{7}}{{{x}+{9}}}&\text{if}&{x}<-{8}\\{7}&\text{if}&{x}=-{8}\\-\frac{{21}}{{{x}+{5}}}&\text{if}&{x}>-{8}\end{array}\right.}

Compute the quantities below. Write "DNE" if the limit does not exist or the value is undefined.

limx8f(x)=\displaystyle \lim_{{{x}\to-{8}^{{-}}}}{f{{\left({x}\right)}}}=  

limx8+f(x)=\displaystyle \lim_{{{x}\to-{8}^{+}}}{f{{\left({x}\right)}}}=  

f(8)=\displaystyle {f{{\left(-{8}\right)}}}=  

Since the above three quantities are , we know that f\displaystyle {f} is at x=8\displaystyle {x}=-{8}.

List ALL numbers at which f\displaystyle {f} is discontinuous. Be sure to check the functions defined to the left and right of -8 for discontinuities.