Question

Solve the system.

5x + 5y – 4z = 13
5x + 3y + z = –3
3x – 2y – z = –10

What are x, y, and z?

Answer 1

A) 5x + 5y – 4z = 13

B) 5x + 3y + z = –3

C) 3x – 2y – z = –10

Adding B) and C) we get equation D

D) 8x + y = -13

Multiplying equation B by 4 we get:

20x + 12y +4 = -12 then adding this to A)

5 x + 5y -4z = 13 we get equation E:

E) 25x + 17y = 1 multiplying equation D by -17 we get

D) -136x -17y = 221 Then we add E and D and get

-111x = 222

x = -2

Putting x = -2 into equation D)

D) 8x + y = -13

D) -16 +y = -13

y = 3

FINALLY we put

x = -2 and y = 3 into equation A)

A) 5*-2 + 5*3 – 4z = 13

A) -10 + 15 -4z = 13

A) -4z = 8

z = -2

Yes, it's just that simple. LOL !!!!!