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Problem3: [Systems of Linear Equations] Determine which of the following equations are linear.

 Problem3: [Systems of Linear Equations] Determine which of the following equations are linear. 

1. $x_1+2x_1x_2+3x_2=4$

2. $\sqrt{x_1}+3x_2=4$

3. $2x_1^{-1}+\sin x_2=0$

4. $3x_1-x_2=x_3+1$

Solution:

1.  Not linear -  contains non linear term $x_1x_2$

2. Not linear -  contains non linear term $\sqrt{x_1}$

3.Not linear -  contains non linear term $x_1^{-1}$

4. Linear - in the form of $a_1x_1 + a_2x_2 + .... + a_nx_n = b$


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