Question

The magnitude of the vector product of the vector i+j+k with a unit vector along the sum of vectors 2i+4j-5k and xi+2j+3k is equal to 2^1/2 . Find the value of x.

Answer 1

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Prasanta Saikia answered this

Let r⃗ =(2iˆ+4jˆ−5kˆ) + (xiˆ+2jˆ+3kˆ)⇒r⃗ =(2+x)iˆ+6jˆ−2kˆ

So, unit vector along the sum mof the 2 vectors=r⃗ ∣∣r⃗ ∣∣=(2+x)iˆ+6jˆ−2kˆ(2+x)2+36+4√