Question

How many solutions does the system of equations have?
3x+12y=20
y=-1/4x+5/3
A) one
B) two
C) infinitely many
D) none

Answer 1

The answer is d) none because substituting -1/4x + 5/3 for y in the first equation gives 3x - 3x + 5/3 = 20 so 5/3 = 20 which is not true.