Question

A system of equations is shown below:

Equation A: 3c = d − 8
Equation B: c = 4d + 8

Which of the following steps should be performed to eliminate variable d first?


A. Multiply equation A by -4.

B. Multiply equation B by 3.

C.. Multiply equation A by 3.

D. Multiply equation B by 4.

Answer 1

A. Multiply equation A by -4;
We obtain : -12c = -4d + 32
c = 4d + 8
______________(+)___
-11c = 42 ( we eliminate variable d first )

Answer 2

Option B is correct.

Explanation:

Given a system of equations is shown below:

`Equation A: 3c = d - 8`

`Equation B: c = 4d + 8`

we have to tell the first step to eliminate the variable d.

To eliminate the variable d we have to make the coefficients of d equal in both the equations.

`Equation A: 3c = d - 8`

`Equation B: c = 4d + 8`

First step is to Multiply equation B by 3 to make equal coefficients.

Hence, option B is correct.