Question

Solve the system of linear equations using the substitution method.

2y + x = -15 and x = 3y

A. (-6, -3)

B. (-7, -6)

C. (-8, -6)

D. (-9, -3)

Answer 1

`{ \green{ \tt{option \: (d)}}}`

Explanation:

Given,

`{ \tt{2y + x = - 15}} \: { \to} \: { \tt {eq}^(n) (1)}`

`{ \tt{x = 3y}} \: { \to} \: { \tt{ {eq}^(n) (2)}}`

Substitute the value of eqⁿ (2) in (1) then,

`{ \tt{2y}} \: + \: { \red{ \tt{3y}}} \: = - 15`

`{ \tt{5y = - 15}}`

Divide both sides by 5 then,

`{ \tt{ (5)/(5)y = - (15)/(5)}}`

`{ \red{ \boxed{ \tt{y = - 3}}}}`

Substitute the value of y in eqⁿ (2)

`{ \tt{x = 3y}}`

`{ \tt{x = 3( - 3)}}`

`{ \red{ \boxed{ \tt{x = - 9}}}}`

Therefore, the value of (x,y) is (-9,-3)

Hence, option (d) is correct.

Answer 2

the answer is D. (-9, -3)