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Provide Solution For  R.D. Sharma Maths Class 12 Chapter  determinants Exercise 5.2 Question 55 Maths Textbook Solution.

Answers (1)

Answer: 9(3 x y z+x y+y z+z x)

Hint: Use determinant formula

Given: \left|\begin{array}{ccc} 1 & 1 & 1+3 x \\ 1+3 y & 1 & 1 \\ 1 & 1+3 z & 1 \end{array}\right|=9(3 x y z+x y+y z+z x)

Solution:

\begin{aligned} &\text { L.H.S }\left|\begin{array}{ccc} 1 & 1 & 1+3 x \\ 1+3 y & 1 & 1 \\ 1 & 1+3 z & 1 \end{array}\right| \\ &\text { Apply } \mathrm{R}_{1} \rightarrow R_{1}-R_{3} \& R_{2} \rightarrow R_{2}-R_{3} \\ &\left|\begin{array}{ccc} 0 & -3 z & 3 x \\ 3 y & -3 z & 0 \\ 1 & 1+3 z & 1 \end{array}\right| \end{aligned}

\begin{aligned} &3 \text { common from } \mathrm{R}_{1} \& R_{2}\\ &3 \times 3\left|\begin{array}{ccc} 0 & -z & x \\ y & -z & 0 \\ 1 & 1+3 z & 1 \end{array}\right| \end{aligned}

\begin{aligned} &\text { Expand from } \mathrm{R}_{1}\\ &9[z(y)+x(y+3 z y+z)\\ &9(3 x y z+x y+y z+z x) \end{aligned}

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