- Home
- Standard 12
- Mathematics
3 and 4 .Determinants and Matrices
medium
નિશ્ચાયકના ગુણધર્મનો ઉપયોગ કરી સાબિત કરો કે, $\left|\begin{array}{ccc}1 & 1+p & 1+p+q \\ 2 & 3+2 p & 4+3 p+2 q \\ 3 & 6+3 p & 10+6 p+3 q\end{array}\right|=1$
Option A
Option B
Option C
Option D
Solution
$\Delta=\left|\begin{array}{ccc}1 & 1+p & 1+p+q \\ 2 & 3+2 p & 4+3 p+2 q \\ 3 & 6+3 p & 10+6 p+3 q\end{array}\right|$
Applying $R_{2} \rightarrow R_{2}-2 R_{1}$ and $R_{3} \rightarrow R_{3}-3 R_{1},$ we have:
$\Delta=\left|\begin{array}{ccc}1 & 1+p & 1+p+q \\ 0 & 1 & 2+p \\ 0 & 3 & 7+3 p\end{array}\right|$
Applying $R_{3} \rightarrow R_{3}-3 R_{2},$ we have:
$\Delta=\left|\begin{array}{ccc}1 & 1+p & 1+p+q \\ 0 & 1 & 2+p \\ 0 & 0 & 1\end{array}\right|$
Expanding along $C_{1},$ we have:
$\Delta=1\left|\begin{array}{cc}1 & 2+p \\ 0 & 1\end{array}\right|=1(1-0)=1$
Standard 12
Mathematics
