CBSE Class 12 Mathematics 2026: question 20
Set in the CBSE Class 12 board exam of 2026, paper 65/5/1, section A, question 20, for 1 mark. Try it first; the hints and our step-by-step solution are below.
Q20 · 1 mark · Assertion-reasonCompetency-basedLinear Programming
Assertion (A) : Consider a Linear Programming Problem with minimise subject to constraints , , which gives minimum Z at infinitely many points. The corner points of feasible region are (0, 3) and (6, 0).
Reason (R) : If two corner points produce the same minimum value of the objective function, then every point on the line segment joining the points will give the same minimum value.
- (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- (C)Assertion (A) is true, but Reason (R) is false.
- (D)Assertion (A) is false, but Reason (R) is true.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 65/5/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
Evaluate Z at both corners.
Hint 2
Region is unbounded — check x+2y<6.
Step-by-step solution
Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.
- ½ mark
Unbounded region with corners (0,3) and (6,0): Z=6 at both. Half-plane x+2y<6 has no common point with region, so min 6 holds on whole segment — infinitely many points. A true.
- ½ mark
R is the standard result that explains A. Option (A).
Answer: Option (A)
Where the marks are
- Z = 6 at both corners, min verified (½ mark)
- R explains A (½ mark)
Revise the chapter
- Chapter: Linear Programming (notes, formulas, where marks are lost and every past question)
- Topic: Corner Point Method
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The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.