a) \(\sqrt{49}+\sqrt{25}-4\cdot0,25\)
\(=7+5-1=11\)
b) \(\sqrt{\frac{1}{9}}\cdot\sqrt{0,81}\cdot\sqrt{0,9}\)
\(=\frac{1}{3}\cdot\frac{9}{10}\cdot\frac{3\sqrt{10}}{10}\)
\(=\frac{9\sqrt{10}}{100}\)
c) \(\sqrt{6,4\cdot2400\cdot0,6}\)
\(=\sqrt{64\cdot36\cdot4}\)
\(=8\cdot6\cdot2=96\)
d) \(\sqrt{26^2-24^2}=\sqrt{\left(26-24\right)\left(26+24\right)}\)
\(=\sqrt{2\cdot50}=\sqrt{100}=10\)