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If veca,vecb,vecc are non-coplanar vecto...

If `veca`,`vecb`,`vecc` are non-coplanar vectors and `lambda` is a real number then
[`lambda(veca+vecb)` `lambda^2vecb` `lambdavecc`] = [`veca` `vecb+vecc` `vecb`] for:

A

(a)exactly two values of `lamda`

B

(b)exactly three values `lambda`

C

(c)no value of `lambda`

D

(d)exactly one value of `lambda`

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The correct Answer is:
To solve the problem, we need to analyze the equation given and simplify it step by step. ### Step 1: Write the Determinant We are given the equation: \[ \begin{vmatrix} \lambda(\vec{a} + \vec{b}) & \lambda^2 \vec{b} & \lambda \vec{c} \\ \end{vmatrix} = \begin{vmatrix} \vec{a} & \vec{b} + \vec{c} & \vec{b} \\ \end{vmatrix} \] ### Step 2: Expand the Left Side The left side can be expanded using the properties of determinants. We can factor out the constants from the determinant: \[ \lambda \cdot \lambda^2 \cdot \lambda = \lambda^4 \begin{vmatrix} \vec{a} + \vec{b} & \vec{b} & \vec{c} \\ \end{vmatrix} \] ### Step 3: Expand the Right Side Now, we expand the right side. The determinant can be rewritten as: \[ \begin{vmatrix} \vec{a} & \vec{b} + \vec{c} & \vec{b} \\ \end{vmatrix} \] This can be simplified using the property of determinants that allows us to replace one column with the sum of two columns: \[ = \begin{vmatrix} \vec{a} & \vec{b} & \vec{b} \\ \end{vmatrix} + \begin{vmatrix} \vec{a} & \vec{c} & \vec{b} \\ \end{vmatrix} \] ### Step 4: Set the Determinants Equal Now we set the two sides equal: \[ \lambda^4 \begin{vmatrix} \vec{a} + \vec{b} & \vec{b} & \vec{c} \\ \end{vmatrix} = \begin{vmatrix} \vec{a} & \vec{b} & \vec{b} \\ \end{vmatrix} + \begin{vmatrix} \vec{a} & \vec{c} & \vec{b} \\ \end{vmatrix} \] ### Step 5: Analyze the Determinants Since \(\vec{a}, \vec{b}, \vec{c}\) are non-coplanar, the determinants will not be zero. Thus, we can analyze the equality of the two sides. ### Step 6: Solve for \(\lambda\) From the equality, we can conclude that: \[ \lambda^4 = 1 \] This implies: \[ \lambda = 1 \quad \text{or} \quad \lambda = -1 \] ### Conclusion Thus, the values of \(\lambda\) that satisfy the equation are \(1\) and \(-1\).
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ARIHANT MATHS ENGLISH-PRODUCT OF VECTORS-Exercise (Questions Asked In Previous 13 Years Exam)
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  3. If vecu, vecv, vecw are non -coplanar vectors and p,q, are real numbe...

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  4. The vector vec a=""alpha hat i+2 hat j+""beta hat k lies in the pl...

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  6. Let bar a= hat i+ hat j+ hat k ,""b= hat i- hat j+2 hat k and bar...

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  7. If (vecaxxvecb)xxvecc=vecaxx(vecbxxvecc), Where veca, vecb and vecc a...

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  8. The values of a for which the points A, B, and C with position vectors...

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  9. The distance between the line r=2hat(i)-2hat(j)+3hat(k)+lambda(hat(i)-...

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  10. If veca is any vector, then (vec a xx vec i)^2+(vec a xx vecj)^2+(ve...

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  11. If veca,vecb,vecc are non-coplanar vectors and lambda is a real number...

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  12. If vec(a)=hat(i)-hat(k), vec(b)=xhat(i)+hat(j)+(1-x)hat(k) vec(c)=yh...

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  13. Let vec u , vec va n d vec w be such that | vec u|=1,| vec v|=2a n d|...

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  14. Let vec(a) , vec(b) and vec(c) be three non-zero vectors such that no ...

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  15. A particle acted by constant forces 4 hat i+ hat j-3 hat k and 3 hat...

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  16. If vec u , vec v and vec w are three non-coplanar vectors, then pro...

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  20. Given, two vectors are hat(i)-hat(j) and hat(i)+2hat(j), the unit vect...

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