I don’t know if you’ve ever heard of the amazing device known as a calculator but the answer is 1,188
A matrix is diagonal if

In other words, you want non-zero elements only when the indices of the row and the column are the same: the first element of the first row must be non zero, the second element of the second row must be non-zero, and so on. All other elements must be zero.
Answer:
It's B :)
Step-by-step explanation:
X equals 6
How? Well first I multiplied 12 x 18 which is 216.
Then I subtracted 468 - 216 that equals 252.
Because I know that 2 x 6 equals a 12.....x had to be a 6.
So I multiplied 42 x 6 and it equaled 252.
So x is 6
(if 2 is a square)
6xy ( x2 - xy + y2)
= 6x3y - 6x2y2 - 6xy3 --------------the threes and twos on this line are squares and cubics. the six is just a whole number