Question

Viết biểu thức sau về dạng bình phương : 
a) 12 - 2\(\sqrt{35}\)
b) 7 + \(\sqrt{40}\)
ai giúp với 

Answer 1

\(12-2\sqrt{35}\)

\(=\left(\sqrt{5}\right)^2+\left(\sqrt{7}\right)^2-2\sqrt{35}\)

\(=\left(\sqrt{5}+\sqrt{7}\right)^2\)

\(7+\sqrt{40}\)

\(=\left(\sqrt{5}\right)^2+\left(\sqrt{2}\right)^2+2\sqrt{10}\)

\(=\left(\sqrt{5}+\sqrt{2}\right)^2\)

Answer 2

a) \(12-2\sqrt{35}=\left(\sqrt{5}\right)^2-2\sqrt{5.7}+\left(\sqrt{7}\right)^2=\left(\sqrt{5}-\sqrt{7}\right)^2\)

b) \(7+\sqrt{40}=7+\sqrt{4.10}=7+2\sqrt{10}=\left(\sqrt{5}\right)^2+2\sqrt{5.2}+\left(\sqrt{2}\right)^2=\left(\sqrt{5}+\sqrt{2}\right)^2\)