Question

Find m if value of given determinant is 21 ​ m 2
​ -5. 7

Answer 1

Answer:

first clear your question bro

Answer 2

Step-by-step explanation:

Given that: if value of given determinant is 21.

$\left|\begin{array}{cc} m&2\\</p><p> -5& 7\end{array}\right|$

To find : Value of m

Solution:Open the determinant

and equate it to 21

$\left|\begin{array}{cc} m&2\\</p><p> -5& 7\end{array}\right|=21$

$7m - 2( - 5) = 21 \\ \\ 7m + 10 = 21 \\ \\ 7m = 21 - 10 \\ \\ 7m = 11 \\ \\\bold{m = \frac{11}{7}}$

Hope it helps you.