Question

помогите help умераю срочно! ​

Answer 1

$\sqrt{18}-\sqrt{50}+\sqrt{72}=\sqrt{9\cdot 2}-\sqrt{25\cdot 5}+\sqrt{36\cdot 2}=\\\\=3\sqrt2-5\sqrt2+6\sqrt2=4\sqrt2\\\\\\3\sqrt{72}-4\sqrt2+2\sqrt{98}=3\sqrt{36\cdot 2}-4\sqrt2+2\sqrt{49\cdot 2}=\\\\=3\cdot 6\sqrt2-4\sqrt2+2\cdot 7\sqrt2=18\sqrt{2}-4\sqrt2+14\sqrt2=28\sqrt2$