Question

How many solutions are there to the following system of equations?

4x – 8y = 0
–3x + 8y = –7

A. 2
B. 1
C. 0
D. infinitely many

Answer 1

`-4x-8y=0\\ \underline{-3x+8y=-7}\\ -7x=-7\\ x=1 \Rightarrow B`

Answer 2

`4x-8y=0 \\ \underline{-3x+8y=-7} \\ 4x-3x=0-7 \\ x=-7 \\ \\ 4x-8y=0 \\ 4 * (-7)-8y=0 \\ -28-8y=0 \\ -8y=28 \\ y=(28)/(-8) \\ y=-(7)/(2) \\ \\ \left \{ {{x=-7} \atop {y=-(7)/(2)}} \right.`

There is one solution to this system of equations. The answer is B.