MCQ
$\begin{vmatrix}\sqrt{14}+\sqrt{3}&\sqrt{20}&\sqrt{5}\\\sqrt{15}+\sqrt{28}&\sqrt{25}&\sqrt{10}\\3+\sqrt{70}&\sqrt {15}&\sqrt{25}\end{vmatrix}= ......$
- A$25\sqrt3 -15\sqrt2$
- B$15\sqrt2 +25\sqrt3$
- C$-25\sqrt3 -15\sqrt2$
- ✓$15\sqrt2 -25\sqrt3$
$D=\begin{vmatrix}\sqrt{14}+\sqrt{3}&\sqrt{20}&\sqrt{5}\\\sqrt{15}+\sqrt{28}&\sqrt{25}&\sqrt{10}\\3+\sqrt{70} &\sqrt{15}&\sqrt{25}\end{vmatrix}$
$=\sqrt{5}(\sqrt{5})\begin{vmatrix}\sqrt{14}+\sqrt{3}&2&1\\\sqrt{15}+\sqrt{28}&\sqrt{5}&\sqrt{2}\\3+\sqrt{70}& \sqrt{3}&\sqrt{5}\end{vmatrix}$
$\xrightarrow[{c_{31}}{(\sqrt{14})}]{c_{21}{(\sqrt{3})}} \ \ \ \ \ \ \therefore c_2(\frac{1}{\sqrt{5}}),c_3(\frac{1}{\sqrt{5}})$
$=5\begin{vmatrix}-\sqrt{3}&2&1\\0&\sqrt{5}&\sqrt{2}\\0&\sqrt{3}&\sqrt{5}\end{vmatrix}$
$=5[-\sqrt{3}(5-\sqrt{6})]$
$=5[3\sqrt{2}-5\sqrt{3}]$
$=15\sqrt{2}-25\sqrt{3}$
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