Question

In some cases, neither of the two equations in the system will contain a variable with a coefficient of 1, so we must take a further step to isolate it. Let's say we now have

3C+4D = 5
2C+5D = 2
None of these terms has a coefficient of 1. Instead, we'll pick the variable with the smallest coefficient and isolate it. Move the term with the lowest coefficient so that it's alone on one side of its equation, then divide by the coefficient. Which of the following expressions would result from that process?
a. C=53−43D
b. C=1−52D
c. D=25−25C
d. D=54−34C

Answer 1

a) C = (5-4D)/3

Step-by-step explanation:

Given the simultaneous equation

3C+4D = 5 .... 1

2C+5D = 2 .... 2

In order to isolate one of the variables, we will make one of the variables in any of the equation.

Using equation 1:

3C+4D = 5

Make C the subject of the formula:

Subtract 4D from both sides of the equation.

3C+4D-4D= 5-4D

3C = 5-4D

Divide both sides by 3:

3C/3 = (5-4D)/3

C = (5-4D)/3

Hence the expression that would result from the process is C = (5-4D)/3