Answer:
Therefore,

Step-by-step explanation:
Given:
![A=\left[\begin{array}{ccc}3&6&9\\2&4&8\\\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D3%266%269%5C%5C2%264%268%5C%5C%5Cend%7Barray%7D%5Cright%5D)
To Find:
a₂₁ = ?
Solution:
Let,
![A=\left[\begin{array}{ccc}a_{11}&a_{12}&a_{13}\\a_{21}&a_{22}&a_{23}\\\end{array}\right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Da_%7B11%7D%26a_%7B12%7D%26a_%7B13%7D%5C%5Ca_%7B21%7D%26a_%7B22%7D%26a_%7B23%7D%5C%5C%5Cend%7Barray%7D%5Cright%5D)
We require ' a₂₁ ' i.e Second Row First Column Element
So on Comparing we get
∴ 
Therefore,

Step-by-step explanation:
a^2 + b^2 = c^2
(x+2)^2 + 4x^2 = (3x+4)^2
(x+2)(x+2)+ 4x^2= (3x+4)(3x+4)
x^2 + 2x + 2x + 4 + 4x^2 = 9x^2 + 12x + 12 x + 16
5x^2 + 4x + 4 = 9x^2 + 24x + 16
-4x^2 - 20x - 12 = 0
now we can use the quadratic formula
(-b±√(b²-4ac))/(2a)
I can't type all this so
.....
x = -0.697224362 or -4.302775638
AB can't be negative so it's the first one
so it's equals to 1.302775638
<u>x = 9</u>
Step-by-step explanation:
mean = 5+7+7+x /4 = 7
19+x / 4 = 7
19+x = 28
x = 9
What is that supposed to mean