[tex] \sqrt{0.4} - \sqrt{1.6} + \sqrt{0.9} = \frac{ \sqrt{10} }{5} - \frac{2 \sqrt{10} }{5} + \frac{3 \sqrt{10} }{10} = \frac{2 \sqrt{10} - 4 \sqrt{10} + 3 \sqrt{10} }{10} = \frac{ \sqrt{10} }{10} [/tex]
[tex] \sqrt{0.04} - \sqrt{1.69} + \sqrt{0.25} = 0.2 - 1.3 + 0.5 = - 0.6[/tex]
