Question

Помогите решить 147 номер

Answer 1

$(\sqrt5-\sqrt{125})^2=5-2\cdot \sqrt5\cdot \sqrt{125}+125=130-2\cdot \sqrt5\cdot 5\sqrt5=\\\\=130-2\cdot 5\cdot 5=130-50=80\\\\\\(\sqrt7+\sqrt{28})^2=7+2\cdot 7\cdot \sqrt{4\cdot 7}+28=35+2\cdot 7\cdot 2\cdot \sqrt7=35+28\sqrt7=\\\\=7\cdot (5+4\sqrt7)\\\\\\(\sqrt{13}-\sqrt{12})(\sqrt{13}+\sqrt{12})=(\sqrt{13})^2-(\sqrt{12})^2=13-12=1$