Question

Áp dụng quy tắc nhân các căn bậc hai, hãy tính :

a) \(\sqrt{10}.\sqrt{40}\)

b) \(\sqrt{5}.\sqrt{45}\)

c) \(\sqrt{52}.\sqrt{13}\)

d) \(\sqrt{2}.\sqrt{162}\)

Answer 1

a) \(\sqrt{10}.\sqrt{40}\)

=\(\sqrt{10.40}\)

=\(\sqrt{400}\)

=20

b) \(\sqrt{5.}\sqrt{45}\)

=\(\sqrt{5.45}\)

=\(\sqrt{225}\)

=\(\sqrt{15}\)

c) \(\sqrt{52.}\sqrt{13}\)

=\(\sqrt{52.13}\)

=\(\sqrt{676}\)

=26

d)\(\sqrt{2.}\sqrt{162}\)

=\(\sqrt{2.162}\)

=\(\sqrt{324}\)

=18

Answer 2

b)

=15

Answer 3

a) \(\sqrt{10}.\sqrt{40}=\sqrt{10.40}=\sqrt{400}=20\)

b) \(\sqrt{5}.\sqrt{45}=\sqrt{5.45}=\sqrt{225}=15\)

c) \(\sqrt{52}.\sqrt{13}=\sqrt{52.13}=\sqrt{676}=26\)

d) \(\sqrt{2}.\sqrt{162}=\sqrt{2.162}=\sqrt{324}=18\)

Answer 4

\(a,\)\(\sqrt{10}.\sqrt{40}=\sqrt{10}.\sqrt{10}.\sqrt{4}=10.2=20\)

\(b,\sqrt{5}.\sqrt{45}=\sqrt{5}.\sqrt{5}.\sqrt{9}=5.3=15\)

\(c,\sqrt{52}.\sqrt{13}=\sqrt{4}.\sqrt{13}.\sqrt{13}=2.13=26\)

\(\sqrt{2}.\sqrt{162}=\sqrt{2}.\sqrt{2}.\sqrt{81}=2.9=18\)