Question

Solve the system of linear equations by substitution.
5x+2y=9
x+y= -3

Answer 1

Explanation:

5x+2y=9.......(1)

x+y= -3.........(2)

Making y as subject bin (2)

y = -3 - x

Substituting in (1)

5x + 2(-3 - x) = 9

5x - 6 - 2x = 9

3x = 9 + 6

3x = 15

x = 15/3

x = 5

And y = -3 - x

y = -3 - 5

y = -8

Answer 2

The solution for the system of linear equations is x = 5, y = -8

Explanation:

Let's solve the system of linear equations by substitution:

5x + 2y = 9

x + y = -3

Solving for x in the 1st equation, this way:

5x + 2y = 9

5x = 9 - 2y

x = (9 - 2y)/5

Substituting x in the 2nd equation:

x + y = -3

(9 - 2y)/5 + y = -3

9 - 2y + 5y = - 15 (Multiplying by 5 at both sides)

3y = - 15 - 9

y = -24/3

y = - 8

Substituting y in the 1st equation:

5x + 2y = 9

5x + 2 * - 8 = 9

5x - 16 = 9

5x = 25

x = 25/5 = 5

The solution for the system of linear equations is x = 5, y = -8