which equation together with x+y=1 forms a system that has a solution of (-3,4)
A)y=x
B) x-y=1
C)y=x=7
D) -3x+4y=1
I think the answer choice is d by sub in the numbers of -3for x and 4fory
no. You want the equation which is true of you sub in -3 and 4.
-3x+4y = -3(-3)+4(4) = 9+16 = 25
Substitute the values for x and y into the other equations and see which produces the result on the right.
For example, it is not A, because that would become
4 = -3
Plus, it might be easier if you fix the typo in C.