Question

Isolating a variable in two equations is easiest when one of them has a coefficient 1.

Let's say we have the two equations:
3A−B = 5
2A+3B = −4
and want to isolate one of the variables, such that it appears by itself on one side of the equation.
Which of the following is an equation with one of the above variables isolated?

a) 3B = -2A-4
b) B = 5-3A
c) B = 3A-5
d) 2A = -3B-4

Answer 1

Option C.

Explanation:

The given equations are

`3A-B=5`

`2A+3B=-4`

We need isolate one of the variables, such that it appears by itself on one side of the equation.

Isolating a variable in two equations is easiest when one of them has a coefficient 1.

In equation 1, coefficient of B is 1. So, we can easily isolate one of the variables.

The equation is

`3A-B=5`

Subtract 3A from both sides.

`-B=5-3A`

Multiply both sides by -1.

`B=3A-5`

Therefore, the correct option is C.