# If number of rows in matrix A is 10 and number of elements = 70 . Also if B has same rows as columns in matrix A . Then find number of columns in B if it has 21 elements

As we have learned

Compact form of matrix -

$\large A= \left [ a_{ij} \right ],$  $\large 1\leq i\leq m$

$1\leq j\leq n$

- wherein

aij - element of the ith row and jth column

m - no. of rows

n - no. of columns

Given $m_A = 10 ; m_A \times n_A= 70$

Thus $n_A= 7$

Also , $m_B= n_A= 7 \; \; and\; \; n_B\times m_B= 21$

Thus  $n_B=3$

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Subscription)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
##### Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
##### Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-