Matrices Quiz 1

Question 1

If $$A=\left( \begin{matrix} 6 & 2 & 3  \ 5 & 2 & 1  \ 3 & 1 & 4  \ \end{matrix} ight)$$, find $$|adjA|$$.

Accepted Answer

$$25$$

Answer

$$49$$

Answer

$$-5$$

Answer

$$7$$

Question 2

If 3 three digit numbers $$P84,6Q3	ext{ and }22R$$ are divisible by 17, where P, Q and R are single digits $$\left( 	ext{from 0 to 9} ight)	ext{,}$$ then the value of the determinant $$\left| 8 \, Q \, 2 \,4 \,3 \,R \,P\, 6 \,2  ight|$$ is;

Accepted Answer

$$0$$

Answer

$$19$$

Answer

$$57$$

Answer

$$-1$$

Question 3

Let $$f\left( x ight)={{x}^{2}}-kx-1$$. If $$A=\left[ \begin{matrix} 3 & 0 & 1  \ 1 & 3 & 2  \ 1 & 1 & 2  \ \end{matrix} ight]$$ and $$f\left( A ight)=\left[ \begin{matrix} 0 & 1 & 2  \ 5 & 1 & 5  \3 & 2 & 0  \ \end{matrix} ight]$$ , find $$k$$.

Accepted Answer

$$3$$

Answer

$$2$$

Answer

$$-2$$

Answer

$$-3$$

Question 4

Given $$A=\left[ \begin{matrix} 2 & 6  \ 1 & 5  \ \end{matrix} ight]$$. If $${{A}^{1}}~=xA+yI$$, where x and y are real numbers and I is the identity matrix of the same order, find $$x+y$$.

Accepted Answer

$$1.5$$

Answer

$$-1$$

Answer

$$2.5$$

Answer

$$-2$$

Question 5

If $$5a+6bc=7a-5b-15c=11a+17b+c=1$$ , then the value of $$a+b+c$$ is:

Accepted Answer

$$3$$

Answer

$$1$$

Answer

$$5$$

Answer

$$7$$