JEE Main 2022 · MathsMultiple choiceSingle correctEasyCalculation

JEE Main 26 July 2022, Shift 2, Maths Q3

Question 3 of 90 in this shift, Maths question 3 of 30, Section A.

Let

A=\begin{bmatrix}1\\1\\1\end{bmatrix}

and

B=\begin{bmatrix}9^2&-10^2&11^2\\12^2&13^2&-14^2\\-15^2&16^2&17^2\end{bmatrix}

, then the value of

A'BA

is:

(1) $1224$
(2) $1042$
(3) $540$
(4) $539$ Official answer

Official answer

Option 4

NTA final key.

Chapter: Matrices
Topic: Matrix Multiplication
Idea tested: Row-by-Column Multiplication

Same idea in other shifts

Asked 3× in all

4 Aug 2021, Shift 1 · Q82Let $M=(a_{ij})_{3\times3}$ , where $a_{ij}=\begin{cases}-1, & i=j\\ i^2-j^2, & i<j\\ 2i-j, & i>j\end{cases}$ $(i, j=1,2,3)$ If…EasyNumerical value
16 Mar 2021, Shift 2 · Q88Let $A=\begin{bmatrix}a_1\\a_2\end{bmatrix}$ and $B=\begin{bmatrix}b_1\\b_2\end{bmatrix}$ be two $2\times1$ matrices with real entries…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.