Answer:
The magnitude is 
The direction is
i.e toward the x-axis
Step-by-step explanation:
From the question we are told that
The function is 
The point considered is 
Generally the maximum rate of change of f at the given point and the direction is mathematically represented as
![\Delta f(x,y) = [\frac{\delta (9sin(xy))}{\delta x} i + \frac{\delta (9sin(xy))}{\delta y} i ]](https://tex.z-dn.net/?f=%5CDelta%20f%28x%2Cy%29%20%3D%20%20%5B%5Cfrac%7B%5Cdelta%20%20%289sin%28xy%29%29%7D%7B%5Cdelta%20x%7D%20i%20%20%2B%20%5Cfrac%7B%5Cdelta%20%20%289sin%28xy%29%29%7D%7B%5Cdelta%20y%7D%20i%20%20%20%5D)
![\Delta f(x,y) = [9y cos (x,y) i + 9xcos (x,y) j]](https://tex.z-dn.net/?f=%5CDelta%20f%28x%2Cy%29%20%3D%20%5B9y%20cos%20%28x%2Cy%29%20i%20%2B%20%209xcos%20%28x%2Cy%29%20j%5D)
At 
![\Delta f (0,8) = [9(8) cos(0* 8)i + 9(8) sin(0* 8)j ]](https://tex.z-dn.net/?f=%5CDelta%20%20f%20%280%2C8%29%20%3D%20%20%5B9%288%29%20cos%280%2A%208%29i%20%20%2B%209%288%29%20sin%280%2A%208%29j%20%20%5D)

Answer:
The matrix is not invertible.
Step-by-step explanation:
We are given the following matrix in the question:
![A =\left[\begin{array}{ccc}-5&0&1\\-1&3&2\\0&10&6\end{array}\right]](https://tex.z-dn.net/?f=A%20%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-5%260%261%5C%5C-1%263%262%5C%5C0%2610%266%5Cend%7Barray%7D%5Cright%5D)
Condition for invertible matrix:
A matrix is invertible if and only if the the determinant is non-zero.
We can find the determinant of the matrix as:
![|A| = -5[(3)(6)-(2)(10)]-0[(-1)(6)-(2)(0)] + 1[(-1)(10)-(3)(0)]\\|A| = -5(18-20)+(-10)\\|A| = 10-10\\|A| = 0](https://tex.z-dn.net/?f=%7CA%7C%20%3D%20-5%5B%283%29%286%29-%282%29%2810%29%5D-0%5B%28-1%29%286%29-%282%29%280%29%5D%20%2B%201%5B%28-1%29%2810%29-%283%29%280%29%5D%5C%5C%7CA%7C%20%3D%20-5%2818-20%29%2B%28-10%29%5C%5C%7CA%7C%20%3D%2010-10%5C%5C%7CA%7C%20%3D%200)
Since the determinant of the given matrix is zero, the given matrix is not invertible.
In d ratio 5:9 which equals 5+9=14
the total female performers is 63
For men = 5/14*63=5/2*9
=45/2 =22.5
The men would be about 22.5 in the dance recital
The answer is 4x-6. Good luck! :D