a)
\frac{\sqrt{10^2-6^2}}{2}=\frac{\sqrt{100-36}}{2}=\frac{\sqrt{64}}{2}=\frac{8}{2}=4
b)
(7+\sqrt9)^2=(7+3)^2=10^2=100
c)
\frac{\sqrt{17^2-8^2}}{5}=\frac{\sqrt{289-64}}{5}=\sqrt{\frac{225}{5}}=\sqrt{45}=\sqrt{9*5}=3\sqrt5
d)
(6-\sqrt4)^2=(6-2)^2=4^2=16