Find the determinant of the matrix.
| 6 9 1 |
| 9 9 2 |
| 2 8 10 ∣

d = -277
d = -278
d = -279
d = -276
d = -272

-276

Step-by-step explanation:

We'll use the method of cofactors.  Use the coefficient +6 for

9   2

8   10

This gives you one third of the solution:  6 {(9)·(10) - (8)(2) },  or 444.

Next, use the coefficient 9, taking care to change the sign to -9  as follows:

     9   1

-9 |           |     =   -9(90 - 8) = -9(82) = -738  

      8  10

Finally with +2 as y our coefficient, evaluate the cofactor

9  1

9  2

ending up with  

+2(18-9) = +2(9) = 18

Finally add these three results together:

+444 - 738 + 18  =  -276

This, the determinant, D, is -276 (the fourth answer choice)

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870