Question

Which of the following ordered pairs represents the solution to the system given below? 2x + y = 20 4x − 2y = 40 A) (10,0) B) (0,10) C) (4,2) D) (10, -10)

Answer 1

$2x+y=20 \ \ \ |\times 2 \\ 4x-2y=40 \\ \\ 4x+2y=40 \\ \underline{4x-2y=40} \\ 4x+4x=40+40 \\ 8x=80 \ \ \ |\div 8 \\ x=10 \\ \\ 2x+y=20 \\ 2 \times 10+y=20 \\ 20+y=20 \ \ \ |-20 \\ y=0 \\ \\ \boxed{(x,y)=(10,0)} \Leftarrow \hbox{answer A}$

Answer 2

Which of the following ordered pairs represents the solution to the system given below?

2x + y = 20 4x − 2y = 40

A. (10,0)