Question

Will give you 30 points answer pls

Answer 1

x = -31,

y = 53,

z = 0

Explanation:

{3x + 2y = 13,

{3x + 2y + z = 13,

{2x + y + 3z = 9;

Make z the subject from the 2nd equation:

z = 13 - 3x - 2y

Replace z in the 3rd equation with its value from the 2nd one:

{3x + 2y = 13,

{2x + y + 3(13 - 3x - 2y) = 9;

Expand brackets:

{3x + 2y = 13,

{2x + y + 39 - 9x - 6y = 9;

Collect like-terms:

{3x + 2y = 13,

{-7x - 5y = -48;

Make y the subject in the 1st equation:

2y = 13 - 3x / : 2

y = 6,5 - 1,5x

Replace y in the 2nd equation with its value from the 1st one:

-7x - 5(6,5 - 1,5x) = -48

Expand brackets:

-7x - 32,5 + 7,5x = -48

Collect like-terms:

0,5x = -15,5 / : 0,5

x = -31

y = 6,5 - 1,5 × (-31) = 53

z = 13 - 3 × (-31) - 2 × 53 = 0