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Gowri Rupal Dar
Asked: 2022-11-11T15:32:47+05:30 In:

Let `veca=(1,1,-1), vecb=(5,-3,-3)` and `vecc=(3,-1,2)`. If `vecr` is collinear with `vecc` and has length `(|veca+vecb|)/(2)`, then `vecr` equals
A. `+-3vecc`
B. `+-3/2vecc`
C. `+-vecc`
D. `+-2/3vecc`

Let `veca=(1,1,-1), vecb=(5,-3,-3)` and `vecc=(3,-1,2)`. If `vecr` is collinear with `vecc` and has length `(|veca+vecb|)/(2)`, then `vecr` equals
A. `+-3vecc`
B. `+-3/2vecc`
C. `+-vecc`
D. `+-2/3vecc`
Parabola
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  1. Correct Answer – C
    We have, `vecr=lambdavecc`
    Given, `|vecr|=|lambda||vecr|`
    `therefore |6hati-2hatj-hatk|=2|lambda||3hati-hatj+2hatk|`
    `therefore sqrt(56) = 2|lambda|sqrt(14)`
    `therefore lambda=+-1`
    `therefore vecr=+-vecc`

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Iqbal Rai
Asked: 2022-10-30T15:53:49+05:30 In:

Let `veca=(1,1,-1), vecb=(5,-3,-3)` and `vecc=(3,-1,2)`. If `vecr` is collinear with `vecc` and has length `(|veca+vecb|)/(2)`, then `vecr` equals
A. `+-3c`
B. `+-(3)/(2)c`
C. `+-c`
D. `+-(2)/(3)c`

Let `veca=(1,1,-1), vecb=(5,-3,-3)` and `vecc=(3,-1,2)`. If `vecr` is collinear with `vecc` and has length `(|veca+vecb|)/(2)`, then `vecr` equals
A. `+-3c`
B. `+-(3)/(2)c`
C. `+-c`
D. `+-(2)/(3)c`
Parabola
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1 Answer

  1. Correct Answer – C
    let `r=lamdac`
    Given `|r|=|lamda||c|`
    `therefore(|a+c|)/(2)=|lamda||c|`
    `therefore|6hati-2hatj-4hatk|=2|lamda|3hati-hatj+2hatk|`
    `therefore sqrt(56)=2|lamda|sqrt(14)`
    `therefore lamda=+-1`
    `therefore r=+-c`.

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