\(b,\)
\(\sqrt{10x^2-12x\sqrt{10}+36}\)
\(=\sqrt{\left(\sqrt{10}x\right)^2-2.x.\sqrt{10}.6+6^2}\)
\(=\sqrt{\left(\sqrt{10}x-6\right)^2}\)
\(=\left|\sqrt{10}x-6\right|\)
Với \(x=\sqrt{\dfrac{5}{2}}+\sqrt{\dfrac{2}{5}}\Rightarrow\left|\sqrt{10}.\left(\sqrt{\dfrac{5}{2}}+\sqrt{\dfrac{2}{5}}\right)-6\right|=1\)
\(e,\)
\(\sqrt{9x^4-24x^2+16}-\sqrt{x^4-8x^2+16}\)
\(=\sqrt{\left(3x^2\right)^2-2.3x^2.4+4^2}-\sqrt{\left(x^2\right)^2-2.x^2.4+4^2}\)
\(=\sqrt{\left(3x^2-4\right)^2}-\sqrt{\left(x^2-4\right)^2}\)
\(=\left|3x^2-4\right|-\left|x^2-4\right|\)
Với \(x=\sqrt{3}\Rightarrow\left|3.\left(\sqrt{3}\right)^2-4\right|-\left|\left(\sqrt{3}\right)^2-4\right|=4\)
b: =|x*căn 10-6|
Khi x=7/căn 10 thì A=|7-6|=1
e: B=|3x^2-4|-|x^2-4|
Khi x=căn 3 thì B=|3*3-4|-|3-4|=5-1=4
