Question

Question 9(Multiple Choice Worth 5 points) (06.01 MC) Solve the system of equations below. x + y = 8 3x + 2y = 21 (3, 5) (5, 3) (2, 6) (6, 2)

Answer 1

Answer:  B.  (5,3)

How to get this answer:

x+y = 8 solves to y = -x+8 after isolating y. You subtract x from both sides.

Plug this into the second equation and solve for x

3x + 2y = 21

3x + 2( y ) = 21

3x + 2( -x+8 ) = 21 ... replace y with -x+8

3x - 2x + 16 = 21

x + 16 = 21

x = 21-16

x = 5

Use this to find y

y = -x+8

y = -5+8

y = 3

We have x = 5 and y = 3 pair up to get the ordered pair solution (5,3)