Start Learning Free

Before You Begin

Question #41695

Difficulty: 8/10 | 🟢 Free

The Question

Let n^=13(i^+j^+k^)\hat{n} = \frac{1}{\sqrt{3}}(\hat{i} + \hat{j} + \hat{k}). A plane Π\Pi in R3\mathbb{R}^3 is defined by the equation r⃗⋅n^=23\vec{r} \cdot \hat{n} = 2\sqrt{3}. A feasible region SS on Π\Pi is bounded by the non-negativity conditions r⃗⋅i^≥0\vec{r} \cdot \hat{i} \ge 0, r⃗⋅j^≥0\vec{r} \cdot \hat{j} \ge 0, r⃗⋅k^≥0\vec{r} \cdot \hat{k} \ge 0, and the following projection constraints: r⃗⋅(i^+2j^)≤8\vec{r} \cdot (\hat{i} + 2\hat{j}) \le 8 r⃗⋅(2i^+3j^−k^)≤14\vec{r} \cdot (2\hat{i} + 3\hat{j} - \hat{k}) \le 14 Determine the maximum value of the objective function Z=r⃗⋅(10i^+24j^+8k^)Z = \vec{r} \cdot (10\hat{i} + 24\hat{j} + 8\hat{k}) for any position vector r⃗∈S\vec{r} \in S.

Options

  • A.

    88

  • B.

    112

  • C.

    128

  • D.

    144

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Specialist

Targeted practice for niche, high-difficulty concepts that frequently appear in JEE Advanced exams.

Concepts Behind This Question

Corner Point Method Precision|Line lying in a plane|Unit Vector Normalization|Collinearity and Coplanarity

Why This Question Is Tricky

Common Mistakes

The problem tests the Corner Point Method in 3D, requiring projection to a 2D plane using Unit Vector Normalization.

The lethal trap lies in the coplanarity and collinearity of the constraints.

When projected, the constraint 2x+3y−z≤142x+3y-z \le 14 becomes 3x+4y≤203x+4y \le 20, which is a linear combination of the other boundaries and is entirely redundant.

If a student blindly pairs equations without checking for redundancy or graphing the feasible region, they will intersect x=0x=0 with 3x+4y=203x+4y=20 to find a 'ghost' vertex at (0,5,1)(0,5,1).

Evaluating the objective function at this invalid vertex yields the trap answer 128, punishing the lack of geometric verification.

Quick Facts About This Question

Question Information

SubjectMathematics
ChapterLinear Programming - Class 12
ConceptCorner Point Method Precision
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree