Practicing Success
Practicing Success
CUET Preparation Today
The values of x for which the angle between the vectors $\vec a=x\hat i-3\hat j-\hat k$ and $\vec b=2x\hat i+x\hat j-\hat k$ is acute and the angle between $\vec b$ and Y-axis lies between $\frac{\pi}{2}$ and $\pi$ are: |
-1 x > 0 1 x < 0 |
x < 0 |
$\vec a.\vec b>0⇒2x^2-3x+1>0⇒(2x-1)(x-1)>0,\,\,\vec b.\hat j<0⇒x<0$ ⇒ Common solution: x < 0 |
