Step-3

Title: System of Linear Equations with Infinite Solutions

Grade: 1400-a Lesson: S1-L7

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step Type Explanation Answer

1

Problem

Show that the following system of equations has an infinite solution: 3x - y = 2 and 9x - 3y = 6.

2

Step

Given system of the equations are

3x - y = 2 Equation (1)

9x - 3y = 6 Equation (2)

3

Formula:

The linear system is

\$ a_1x + b_1y = c_1 \$

\$ a_2x + b_2y = c_2 \$

4

Hint

By comparing with the linear system, we get

\$ a_1 = 3, b_1 = -1 ,c_1 = 2 , a_2 = 9 , b_2 = - 3 ,c_2 = 6 \$

5

Step

Now, the ratios are:

\$ (a_1/a_2) = \cancel (3)^1 / (\ cancel (9)^2) = 1/3 \$
\$ (b_1/b_2) = -1 /-3 = 1/3 \$
\$ (c_1/c_2) = \cancel2^1/(\cancel6^3) = 1/3 \$
\$ (a_1/a_2) = (b_1/b_2) = (c_1/c_2) \$

6

Step

Therefore, the given system of equations has infinitely many solutions.

7

Choice.A

This is correct because Equation 2 is a multiple of Equation 1, making the ratios of corresponding coefficients equal

\$ (a_1)/(a_2) = (b_1)/(b_2) = (c_1)/(c_2) \$

8

Choice.B

This is incorrect because the coefficients ratios in Equation 2 are proportional to Equation 1

\$ (a_1)/(a_2) ne (b_1)/(b_2) = (c_1)/(c_2) \$

9

Choice.C

This is incorrect because the coefficients ratio in Equation 2 is a multiple of Equation 1

\$ (a_1)/(a_2) = (b_1)/(b_2) ne (c_1)/(c_2) \$

10

Choice.D

This is incorrect because Equation 2 is a multiple of Equation 1, indicating unequal coefficients

\$ (a_1)/(a_2) ne (b_1)/(b_2) ne (c_1)/(c_2) \$

11

Answer

Option

A

12

Sumup

Can you summarize what you’ve understood in the above steps?


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