Select the best possible first step to solving the system by first eliminating the x variable. 4x 9y = 21 3x − 8y = 1 multiply the first equation by 3, and multiply the second equation by 4. multiply the first equation by −3, and multiply the second equation by −4. multiply the first equation by 8, and multiply the second equation by 9. none of the above

 The correct option is

(A) multiply the first equation by 3, and multiply the second equation by 4.

Step-by-step explanation: The given system of linear equations is:

We are to select the best possible first step to solve the above system by first eliminating x variable.

Since, we need to eliminate x variable first, so will try to make the coefficients of x in both the equations equal. After that, we will subtract one of the equations from the other to eliminate x.

The co-efficient of x in equation (i) is 4,

and

the co-efficient of x in equation (ii) is 3.

So, to make both of them same, we will take the LCM of the coefficients 4 and 3.

We have

LCM(4, 3) = 12.

Now, we will multiply equation (i) by 3 and equation (ii) by 4 to make both the coefficients in equation (i) and (ii) equal to 12.

Thus, we will multiply first equation by 3 and second equation by 4.

Option (A) is CORRECT.