Quiz: Linear Equations and Matrix Entreis
by Yu · Published · Updated
Problem 86
Do the following quiz about
 Linear Equations
 Matrix entries.
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Question 1 of 2
1. Question
Which of the following equations are linear? (Multiple choice)
Correct
Good!! The equation (a), (c), and (e) are linear.
For (c), note that we can cancel the term $x_1x_2$. For (e), note that $\cos^2x_3+\sin^2 x_3=1$.
For other equations, the terms $x_2^2, x_3^3, x_1x_2, x_2x_3, x_3x_4$ are nonlinear.Incorrect
The equation (a), (c), and (e) are linear.
For (c), note that we can cancel the term $x_1x_2$. For (e), note that $\cos^2x_3+\sin^2 x_3=1$.
For other equations, the terms $x_2^2, x_3^3, x_1x_2, x_2x_3, x_3x_4$ are nonlinear. 
Question 2 of 2
2. Question
Let $A=(a_{ij})=\begin{bmatrix}
1 & 2 & 3 & 4 &5 \\
6 & 7 & 8 & 9 & 10 \\
11 & 12 & 13 & 14 & 15 \\
16 & 17 & 18 & 19 & 20 \\
21 & 22 & 23 & 24 & 25
\end{bmatrix}$ be a $5\times 5$ matrix.
Find the following entries. $a_{21}$
 $a_{33}$
 $a_{14}$
 $a_{53}$
 $a_{12}$
 $a_{41}$
 $a_{35}$
 $a_{42}$
Sort elements
 6
 13
 4
 23
 2
 16
 15
 17

$a_{21}$

$a_{33}$

$a_{14}$

$a_{53}$

$a_{12}$

$a_{41}$

$a_{35}$

$a_{42}$
Correct
Good!! Recall that $a_{ij}$ is the entry of $A$ in the $i$th row and $j$th column.
Incorrect
Recall that $a_{ij}$ is the entry of $A$ in the $i$th row and $j$th column.
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