Question

Solve the following systems of linear equations using substitution.

5x + y = -13 and -5x - 6y = -22

Answer 1

x = -4, y = 7

Explanation:

The two equations are:

5x + y = -13 ... (1)

-5x - 6y = -22 ...(2)

Isolate for x in (1)

5x + y = -13

5x = -13 -y

x = (-13-y)/5

Substitute this value of x into equation (1) -5x - 6y = -22

-5 · (-13-y)/5 -6y = -22

-1(-13-y) - 6y = -22

13 + y -6y = -22

y - 6y = -22 - 13

-5y = - 35

y = -35/-5 = 7

Substitute y = 7 in equation 1
5x + 7 = -13

5x = -13 - 7

5x = -20

x = 20/-5 = -4

Ans:

x = -4, y = 7