JEE Main 2020MathematicsDeterminantsEasyMCQ

JEE Main 2020 — Determinants Question with Solution

JEE Main 2020 (09 Jan Shift 1)

Question

If for some α and β in R , the intersection of the following three planes
x+4y-2z=1
x+7y-5z=β
x+5y+αz=5
is a line in R3 , then α+β is equal to:

Choose an option

Show full solutionCorrect option: B
Correct answer
B10

Step-by-step explanation

∆=0⇒14-217-515α=0
7α+25-4α+10+-20+14=0
3α+9=0⇒α=-3
Also Dz=0⇒14117β155=0
135-5β-15+14β-7=0
β=13

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About this question

This is a previous-year question from JEE Main 2020, covering the Determinants chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.