Question

На фото 8 класс алгебра

Answer 1

$\displaystyle\bf\\1)\\\\\sqrt{4c} -\sqrt{9c} +\sqrt{49c} =\sqrt{2^{2}\cdot c } -\sqrt{3^{2}\cdot c } +\sqrt{7^{2}\cdot c } =\\\\\\=2\sqrt{c} -3\sqrt{c} +7\sqrt{c} =6\sqrt{c} \\\\2)\\\\3\sqrt{2a} -\sqrt{18a} =3\sqrt{2a} -\sqrt{9\cdot 2a} =3\sqrt{2a} -\sqrt{3^{2} \cdot 2a} =\\\\\\=3\sqrt{2a} -3\sqrt{2a}=0$