Mathematics · 2020
JEE Main · 2 September 2020, Shift 2 · Q55
Let A ={ X =(x, y, z)^T: PX =0. and.x^2+y^2+z^2=1}, where P = [1, 2, 1; -2, 3, -4; 1, 9, -1], then the set A:
Let $\displaystyle \mathrm{A}=\left\{\mathrm{X}=(x, y, z)^{\mathrm{T}}: \mathrm{PX}=0\right.$ and $\displaystyle \left.x^2+y^2+z^2=1\right\}$, where $\displaystyle \mathrm{P}=\left[\begin{array}{rrr}1 & 2 & 1 \\ -2 & 3 & -4 \\ 1 & 9 & -1\end{array}\right]$, then the set A :
Official answer
(3)
contains exactly two elements.
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JEE Main 2020 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.