Question

√45 + √80 -√105

Answer 1

Ta có : \(\sqrt{45}+\sqrt{80}-\sqrt{105}\)

\(=3\sqrt{5}+4\sqrt{5}-\sqrt{105}=7\sqrt{5}-\sqrt{105}\)

\(=\sqrt{5}\left(7-\sqrt{21}\right)\)

Answer 2

\(\sqrt{45}+\sqrt{80}-\sqrt{105}=3\sqrt{5}+4\sqrt{5}-\sqrt{105}=7\sqrt{5}-\sqrt{105}=\sqrt{5}\left(7-\sqrt{21}\right)\)