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[tex] \sqrt{18} [/tex] + [tex]3 \sqrt{50} [/tex] + [tex] \sqrt{98} [/tex]

[tex]\sqrt{18} +3 \sqrt{50}+ \sqrt{98}\\ = \sqrt{2*9} +3 \sqrt{25*2} + \sqrt{2*49}\\ = 3\sqrt{2} +3*5 \sqrt{2} + 7 \sqrt{2} \\=3 \sqrt{2} +15 \sqrt{2} +7 \sqrt{2} \\ \boxed{ =25\sqrt{2} }[/tex]

[tex] \sqrt{18}+3 \sqrt{50}+ \sqrt{98}= \\ 18|2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~50|5^2=>5\\ ..9|3^2=>3.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~2|2 \\ \sqrt{18}=3 \sqrt{2} ~~~~~~~~~~~~~~~~~~~~~~~~~~~~3 \sqrt{50}=3*5 \sqrt{2}=15 \sqrt{2} \\ \\ 98|2 \\ 49|7^2=>7 \\ \sqrt{98}=7 \sqrt{2} \\ \\ 3 \sqrt{2}+15 \sqrt{2}+7 \sqrt{2}=\boxed{25 \sqrt{2} } [/tex]