Tính 13 căn bậc hai của 2  - 4 căn bậc hai của 6 /24 - 4 căn bậc hai của 3

Trả lời

Lời giải:

\(\frac{{13\sqrt 2 - 4\sqrt 6 }}{{24 - 4\sqrt 3 }} = \frac{{\left( {13\sqrt 2 - 4\sqrt 6 } \right)\left( {24 + 4\sqrt 3 } \right)}}{{\left( {24 - 4\sqrt 3 } \right)\left( {24 + 4\sqrt 3 } \right)}}\)

\( = \frac{{13\sqrt 2 .24 + 13\sqrt 2 .4\sqrt 3 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{\left( {24 - 4\sqrt 3 } \right)\left( {24 + 4\sqrt 3 } \right)}}\)

\( = \frac{{13\sqrt 2 .24 + 13\sqrt 2 .4\sqrt 3 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{{{24}^2} - {{\left( {4\sqrt 3 } \right)}^2}}}\)

\( = \frac{{13\sqrt 2 .24 + 13\sqrt 2 .4\sqrt 3 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{576 - {{\left( {4\sqrt 3 } \right)}^2}}}\)

\( = \frac{{13\sqrt 2 .24 + 13\sqrt 2 .4\sqrt 3 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{576 - 48}}\)

\( = \frac{{312\sqrt 2 + 13\sqrt 2 .4\sqrt 3 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{576 - 48}}\)

\( = \frac{{312\sqrt 2 + 52\sqrt 6 - 4\sqrt 6 .24 - 4\sqrt 6 .4\sqrt 3 }}{{576 - 48}}\)

\( = \frac{{312\sqrt 2 + 52\sqrt 6 - 96\sqrt 6 - 4\sqrt 6 .4\sqrt 3 }}{{576 - 48}}\)

\( = \frac{{312\sqrt 2 + 52\sqrt 6 - 96\sqrt 6 - 48\sqrt 2 }}{{576 - 48}}\)

\( = \frac{{264\sqrt 2 + 52\sqrt 6 - 96\sqrt 6 - 48\sqrt 2 }}{{528}} = \frac{{264\sqrt 2 - 44\sqrt 6 }}{{528}}\)

\( = \frac{{44\left( {6\sqrt 2 - \sqrt 6 } \right)}}{{44.12}} = \frac{{6\sqrt 2 - \sqrt 6 }}{{12}}\)