Question

Dùng bảng căn bậc hai tìm \(x\), biết :

a) \(x^2=15\)

b) \(x^2=22,8\)

c) \(x^2=351\)

d) \(x^2=0,46\)

Answer 1

a) \(x^2=15\)

\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{15}\\x=-\sqrt{15}\end{matrix}\right.\)

b) \(x^2=22,8\)

\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{22,8}\\x=-\sqrt{22,8}\end{matrix}\right.\)

c) \(x^2=351\)

\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{351}=3\sqrt{39}\\x=-\sqrt{351}=-3\sqrt{39}\end{matrix}\right.\)

d) \(x^2=0,46\)

\(\Rightarrow\left[{}\begin{matrix}x=\sqrt{0,46}\\x=-\sqrt{0,46}\end{matrix}\right.\)

Answer 2

a) x=\(\sqrt{15}\)

_{b) X=\(\sqrt{22.8}\)}

c) x=\(\sqrt{351}\)

d) x=\(\sqrt{0.46}\)