Question

Perform an operation on the given system that eliminates the indicated variable. Write the new equivalent system.

2x + y − 4z = 4, 2x + 4y + z = 15, 6x − 5y − z = 7
Eliminate the x-term from the third equation.

Answer 1

8y-11z=5

Explanation:

2x + y − 4z = 4, -----------A

2x + 4y + z = 15,-----------B

6x − 5y − z = 7------------C

Solving A to find the value of x

2x= 4-y+4z

x=4-y+4z/2------------------D

Putting D in C

6(4-y+4z/2) -5y -z=7

3(4-y+4z) -5y-z=7

12-3y+12z-5y-z=7

12-8y + 11z=7

-8y +11z= 7-12

-8y +11z= -5

8y-11z=5--------------E