Triangularizing matrix gives the matrix that has only zeroes above or below the main diagonal. To find which option is correct we need to calculate all of them.
In all these options we calculate result and write it into row that is first mentioned:
A)R1-R3
![\left[\begin{array}{ccc}-1&0&0|0\\0&1&1|6\\2&0&1|1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-1%260%260%7C0%5C%5C0%261%261%7C6%5C%5C2%260%261%7C1%5Cend%7Barray%7D%5Cright%5D%20)
B)2R2-R3
![\left[\begin{array}{ccc}1&0&1|1\\-2&2&1|4\\2&0&1|1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%260%261%7C1%5C%5C-2%262%261%7C4%5C%5C2%260%261%7C1%5Cend%7Barray%7D%5Cright%5D%20)
C)-2R1+R3
![\left[\begin{array}{ccc}0&0&-1|-1\\0&1&1|6\\2&0&1|1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D0%260%26-1%7C-1%5C%5C0%261%261%7C6%5C%5C2%260%261%7C1%5Cend%7Barray%7D%5Cright%5D%20)
D)2R1+R3
![\left[\begin{array}{ccc}4&0&3|3\\0&1&1|6\\2&0&1|1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D4%260%263%7C3%5C%5C0%261%261%7C6%5C%5C2%260%261%7C1%5Cend%7Barray%7D%5Cright%5D%20)
E)3R1+R3
![\left[\begin{array}{ccc}5&0&4|4\\0&1&1|6\\2&0&1|1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D5%260%264%7C4%5C%5C0%261%261%7C6%5C%5C2%260%261%7C1%5Cend%7Barray%7D%5Cright%5D%20)
None of the options will triangularize this matrix. The only way to <span>triangularize this matrix is
R3-2R1
</span>
![\left[\begin{array}{ccc}1&0&1|1\\0&1&1|6\\0&0&-1|-1\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%260%261%7C1%5C%5C0%261%261%7C6%5C%5C0%260%26-1%7C-1%5Cend%7Barray%7D%5Cright%5D%20%20)
<span>
This equation is similar to C) but in reverse order. Order in which rows are written is important.</span>
 
        
        
        
Volume of the outer cylinder = 3.14 x (1.5)² x 18 = 127.17 ft²
Volume of the inner cylinder = 3.14 x (1)² x 18 = 56.52 ft²
Volume of the pipe = 127.17  -  56.52 = 70.65 ft²
Answer: 70.65 ft²
        
             
        
        
        

Degree of a polynomial is the highest exponential power in the expression. 
i.e 9 here 
so, degree of the given expression is 9 
 
        
             
        
        
        
So, we start off with this:

First, use the distributive property on the right side of the equation:

We can then simplify 

 to just 9. Now, our equation is:

Add 9 to both sides:

And finally, divide both sides by 7:

And there you have it! Hope I helped, let me know if you have any questions :)