Which system of equations is (–3, 19) and (4, –23) equal to?

Question

anonymous · Answer

A.y=x^2+7x+11 
y=6x-1 

B. y=x^2-7x+11 
y=6x+1 

C.-x^2+7x-11 
y=6x-1 

D.y=x^2-7x-11 
y=-6x+1

whpalmer4 · Answer

You mean which system of equations have those two pairs of numbers as solutions.

Plug each pair of numbers into each of the equations in a given system.  If they all produce true number sentences, then it is a solution; otherwise, it isn't.  

Given that you have a multiple choice format answer here, you might try plugging the numbers into the second equation in each one first, so you can discard candidates more easily.

anonymous · Answer

that was what i needed to know how to do it thank u

whpalmer4 · Answer

What did you get for the answer?

anonymous · Answer

i believe it is c

whpalmer4 · Answer

No....you couldn't possibly have tried the points in the equations successfully and chosen C, I'm afraid :-(

C has two equations:$$y=-x^2+7x-11$$and$$y=6x-1$$
We have two points to try: $(-3,19) \text{ and } (4,-23)$

$$y = -x^2+7x-11$$$$19 = -(-3)^2+7(-3)-11$$$$19 = -9 -21 -11$$Uh, no.

$$y = 6x-1$$$$19=6(-3)-1$$$$19=-19$$Also no.  You're trying to find a set of equations that make valid number sentences when you plug in the point.

Maybe you tried the other point?

$$-23 = -(4)^2+7(4)-11$$$$-23=-16+28-11$$$$-23 = 1$$Nope, doesn't look like you tried the other point, either.
$$-23 = 6(4) -1$$$$-23 = 23$$