Step-2

Title: System of Linear Equations with no Solutions

Grade: 1300-a Lesson: S1-L8

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

Lesson Steps

Step Type Explanation Answer

1

Problem

If there is no solution to the linear equation system
3a - b = 2, ma + 4b = 8, then find the value of m?

2

Step

Consider the two linear equations are

\$ a_1x + b_1x = c_1 \$ …​…​.eq (1)
\$ a_2x + b_2x = c_2 \$ …​…​.eq (2)

3

Formula:

If equation (1) and equation (2) have no solution then we can write,

\$ a_1/a_2 = b_1/b_2 ne c_1/c_2 \$ …​…​.equation (3)

4

Hint

First, we will compare 3a - b = 2 with equation (1)
and ma + 4b = 8 with equation (2).
So by comparing the coefficients, we can write

\$a_1 = 3,a_2 = m\$,
\$b_1 = - 1,b_2 = 4\$,
\$c_1 = 2,c_2 = 8\$

5

Clue

Now substitute the values in equation (3)

\$ 3/m = - 1/4 ne 2/8 \$ …​…​.equation (3)

6

Step

Now taking the first two parts of the above equation, we get

\$ 3/m = - 1/4 \$

7

Step

After cross-multiplication and simplification, we get

12 = - m
- 12 = - (- m)
m = - 12

8

Step

Therefore, the value of m is - 12.

9

Choice.A

Choice A is incorrect. This value would not make the coefficients of a and b proportional in the same manner as required for no solution

\$m = 1/12\$

10

Choice.B

Choice B is incorrect. After inspecting the coefficients, we found that the value of 'm' does not meet the required condition

\$m = -1/12\$

11

Choice.C

Choice C is correct. After analyzing the coefficients, we verified that the value of m is appropriate, maintaining the validity of the equality

m = - 12

12

Choice.D

Choice D is incorrect. Upon examining the coefficients, we found that the value of m does not meet the required condition

m = 12

13

Answer

Option

C

14

Sumup

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


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