Question

Trục căn thức ở mẫu a) -2/3√11 b) 3/√7+4

Answer 1

a) `-2/(3\sqrt11) = (-2\sqrt11)/(3\sqrt11 .\sqrt11) =(-2\sqrt11)/(3.11)=(-2\sqrt11)/33`

b) `3/(\sqrt7+4) = (3.(\sqrt7-4))/((\sqrt7+4)(\sqrt7-4))`

`=(3.(\sqrt7-4))/((\sqrt7)^2-4^2)`

`=(3.(\sqrt7-4))/(-9)`

`=(4-\sqrt7)/3`

Answer 2

\(\dfrac{-2}{3\sqrt{11}}=\dfrac{-2\sqrt{11}}{33}\)

\(\dfrac{3}{4+\sqrt{7}}=\dfrac{12-3\sqrt{7}}{7}\)