3-1.Vectors
hard

સદિશ $a \hat{i}+b \hat{j}+\hat{k}$ અને $2 \hat{i}-3 \hat{j}+4 \hat{k}$ જયારે $3 a+2 b=7$ હોય, ત્યારે લંબ હોય છે, $a$ અને $b$ નો ગુણોત્તર $\frac{x}{2}$ છે. તો $x$ નું મૂલ્ય $...........$ છે.

A

$1$

B

$2$

C

$3$

D

$4$

(JEE MAIN-2023)

Solution

For two perpendicular vectors

$(a \hat{i}+b \hat{j}+\hat{k}) \cdot(2 \hat{i}-3 \hat{j}+4 \hat{k})=0$

$2 a-3 b+4=0$

On solving, $2 a-3 b=-4$

Also given

$3 a+2 b=7$

We get $a =1, b =2$

$\frac{ a }{ b }=\frac{ x }{2} \Rightarrow x =\frac{2 a }{ b }=\frac{2 \times 1}{2}$

$\Rightarrow x =1$

Standard 11
Physics

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