MHT CET · Maths · Vector Algebra
If \(\bar{a}+2 \bar{b}+3 \bar{c}=\overline{0}\) and \((\bar{b} \times \bar{b})+(\bar{b} \times \bar{c})+(\bar{c} \times \bar{a})=\lambda(\bar{b} \times \bar{c})\), then \(\lambda\) has the value
- A 4
- B 5
- C 3
- D 6
Answer & Solution
Correct Answer
(D) 6
Step-by-step Solution
Detailed explanation

\(\Rightarrow(\vec{a}+\vec{b}+\vec{c}) \times(\vec{a}+2 \vec{b}+3 \vec{c})=\overrightarrow{0} \)
\( \Rightarrow 2 \vec{a} \times \vec{b}+3 \vec{a} \times \vec{c}+\vec{b} \times \vec{a}+3 \vec{b} \times \vec{c}+\vec{c} \times \vec{a}~+\) \(2 \vec{c} \times \vec{b}=\overrightarrow{0} \)
\( \Rightarrow \vec{a} \times \vec{b}+\vec{b} \times \vec{c}-2 \vec{c} \times \vec{a}=\overrightarrow{0} \)
\( \Rightarrow \vec{a} \times \vec{b}+\vec{b} \times \vec{c}+\vec{c} \times \vec{a}=3 \vec{c} \times \vec{a}=3 \vec{c} \times(-2 \vec{b}-3\)\(\vec{c}) \quad[\text { from (1)] } \)
\( \Rightarrow \vec{a} \times \vec{b}+\vec{b} \times \vec{c}+\vec{c} \times \vec{a}=-6 \vec{c} \times \vec{b} \)
\( \Rightarrow \vec{a} \times \vec{b}+\vec{b} \times \vec{c}+\vec{c} \times \vec{a}=6 \vec{b} \times \vec{c} \)
\( \Rightarrow \lambda=6\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Maths
- The co-ordinates of the \(\mathrm{P} \equiv(1,2,3)\) and \(\mathrm{O} \equiv(0,0,0)\), then the direction cosines of \(\overline{\mathrm{OP}}\) areMHT CET 2021 Easy
- The equation of the line, through \(A(1,2,3)\) and perpendicular to the vector \(2 \hat{i}+\hat{j}-\hat{k}\) and \(\hat{i}+3 \hat{j}+2 \hat{k}\), isMHT CET 2024 Easy
- The differential equation of all parabolas, whose axes are parallel to \(\mathrm{Y}\)-axis, isMHT CET 2023 Easy
- The particular solution of the differential equation , when isMHT CET 2017 Easy
- If \(y=\log \sqrt{\frac{1+\sin x}{1-\sin x}}\), then \(\frac{d y}{d x}\) at \(x=\frac{\pi}{3}\) isMHT CET 2022 Medium
- Let PQ and RS be tangents at the extremities of the diameter PR of a circle of radius r. If PS and RQ intersect at a point \(X\) on the circumference of the circle, then 2 r equalsMHT CET 2024 Medium
More PYQs from MHT CET
- A person measures a time period of a simple pendulum inside a stationary lift and finds it to be T. If the lift starts accelerating upwards with an acceleration the time period of the pendulum will beMHT CET 2019 Medium
- When tert butyl bromide is heated with silver fluoride the major product obtained isMHT CET 2025 Easy
- If \(F(\propto)=\left[\begin{array}{ccc}\cos \propto & -\sin \propto & 0 \\ \sin \propto & \cos \propto & 0 \\ 0 & 0 & 1\end{array}\right]\), where \(\propto \in R\), then \([F(\propto)]^{-1}\)MHT CET 2021 Medium
- Which of the following is correct IUPAC name of catechol?MHT CET 2025 Easy
- Using variation of force and time given below, final velocity of a particle of mass \(2 \mathrm{~kg}\) moving with initial velocity \(6 \mathrm{~m} / \mathrm{s}\) will be
MHT CET 2023 Medium - In Young's double slit experiment, the intensity on screen at a point, where path difference is \(\frac{\lambda}{4}\) is \(\frac{K}{4}\). The intensity at a point when path difference is ' \(\lambda\) ' will be \(\left[\cos \frac{\pi}{2}=0, \cos 2 \pi=1\right]\)MHT CET 2025 Medium