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Vector Algebra question

2021 · 16 Mar · Shift 2 · Q26

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PYQ Library
JEE Main
Mathematics
Vector Algebra
2021 · 16 Mar · Shift 2 · Q26

Vector Algebra question

2021 · 16 Mar · Shift 2 · Q26

JEE MainMathematicsVector AlgebraMCQ+4 / −1

Let

\overrightarrow a

=

\widehat i

+ 2

\widehat j-

3

\widehat k

and

\overrightarrow b = 2\widehat i-

3

\widehat j

+ 5

\widehat k

. If

\overrightarrow r \times\overrightarrow a

=

\overrightarrow b \times\overrightarrow r

,

\overrightarrow r

.

\left( {\alpha \widehat i + 2\widehat j + \widehat k} \right)

= 3 and

\overrightarrow r \,.\,\left( {2\widehat i + 5\widehat j - \alpha \widehat k} \right)

=

-

1,

\alpha\in

R, then the value of

\alpha

+

{\left| {\overrightarrow r } \right|^2}

is equal to :

A
13
B
11
C
9
D
15

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