HELPPP A system of equations is given below:

x + 2y = 7
-3x + 4y = 9

Nicole says she would multiply the first equation by 3 and add the two equations together to eliminate the x's. Michael says he would multiply the first equation by 2 and add the two equations to eliminate the y's.

Who is correct? and explain why.

Nicole is correct, since when she multiplied by 3, she cleared the x's, since one x was already negative, and the other one was positive. Michael is incorrect since when he multiplied by 2, he didn't realize that both y's were positive, so they didn't clear.

Step-by-step explanation:

Let's see what will happen if we do what Nicole says:

x+2y=7

-3x+4y=9

multiply the first equation by 3 on both sides

3(x+2y)=7(3)

3x+6y=21

-3x+4y=9

now let's add them.

10y=30

We can see that the x's are cleared, since one x is positive and the other is negative.

Now let's try what Michael says.

x+2y=7

-3x+4y=9

multiply first equation by 2

2(x+2y)=7

2x+4y=7

-3x+4y=9

now let's add

-x+8y=16

the y's aren't eliminated, since both of them are positive.

Nicole is correct, since one x is positive and another was negative, and when opposite numbers are added together, they  cancel out and equal zero.

Hope this helps!

One solution graph is when the graphs of the equations intersect, then there is one solution that is true for both equations.  

One solution = lines intersect

No solution graph is when the graphs of the equations do not intersect (for example, if they are parallel), then there are no solutions that are true for both equations.

No solution: lines are parallel

Infinitive solution graph is when the graphs of the equations are the same, then there are an infinite number of solutions that are true for both equations.

Infinitive solutions: One line