The value of m for which volume of the parallelopiped is 4 cubic units whose three edges are represented by a=mi+j+k, b=i−j+k, c=i+2j−k is
Explanation
Solution:
The volume of a parallelepiped with adjacent edges a,b,c is given by the magnitude of their scalar triple product:
V=∣[a b c]∣=4
The scalar triple product is calculated using the determinant:
m11amp;1amp;−1amp;2amp;1amp;1amp;−1=±4
Expanding along the first row:
m[(−1)(−1)−(1)(2)]−1[(1)(−1)−(1)(1)]+1[(1)(2)−(−1)(1)]=±4
m[1−2]−1[−1−1]+1[2+1]=±4
−m+2+3=±4
5−m=±4
Case 1:
5−m=4
m=1
Case 2:
5−m=−4
m=9
Comparing with the given options, m=1 is the correct value.
Correct Option: (D)
Explanation
Solution:
The volume of a parallelepiped with adjacent edges a,b,c is given by the magnitude of their scalar triple product:
V=∣[a b c]∣=4
The scalar triple product is calculated using the determinant:
m11amp;1amp;−1amp;2amp;1amp;1amp;−1=±4
Expanding along the first row:
m[(−1)(−1)−(1)(2)]−1[(1)(−1)−(1)(1)]+1[(1)(2)−(−1)(1)]=±4
m[1−2]−1[−1−1]+1[2+1]=±4
−m+2+3=±4
5−m=±4
Case 1:
5−m=4
m=1
Case 2:
5−m=−4
m=9
Comparing with the given options, m=1 is the correct value.
Correct Option: (D)