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Help with these questions

Help with these questions-example-1
User Rwitzel
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1 Answer

4 votes

9514 1404 393

Answer:

16) No

17) (c)

Explanation:

For a lot of multiple-choice matrix problems, a simple test is all that is needed to determine the correct answer.

16) The determinant of A is (-2)(-2) -(2)(-3) = 10. So, we expect to see values in the inverse matrix that are 0.2 and 0.3. Alas, they're not there. The matrices are not inverses.

A^-1 = [[-.2, .3][-.2, -.2]]

__

17) The matrices are both 3×3, so their product is possible (eliminates choice D). The upper left term is different among the answer choices, so we can determine the correct one by computing that term only.

BA=C

c11 = (5)(1) +(7)(5) +(3)(-1) = 5 +35 -3 = 37

This matches the third choice (C).

If you use a calculator to compute the full matrix product, it matches choice C in all details.

User Nakilon
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