Question

Solve using linear combination

x-y=-7
x+y=7

A. (-7,0)
B. (7,0)
C. (0,7)
D. (0,-7)

Answer 1

add them equationas and y's cancel

x-y=-7
x+y=7 +
2x+0y=0

2x=0
x=0

so

0+y=7
y=7

(x,y)
x=0, y=7
(0,7)


C