8th grade math, I'd appreciate some help. ;)

Question

rebeccaxhawaii · Answer

whats up

impracticaljoker · Answer

Jordan wants to solve the following system using the elimination method:

2x + 3y = 10
x + y = 7

What number should the equation x + y = 7 be multiplied by to eliminate y? (4 points)
   


  –2  


  2  


  –3  


  3

4everaddicted2anime · Answer

In order to eliminate y, both y's have to have the same coefficient. You have y and then you have 3y. What do you have to multiply y by to get 3y?

phi · Answer

this is a lousy question.  You could multiply the bottom equation by 3 and then
subtract, i.e. do  top equation - bottom equation

or, you could multiply the bottom equation by -3 and then add:  top equation plus bottom equation.

I am *guessing* they assume  you add the two equations, but who knows?  I would complain to the teacher about this.

directrix · Answer

2x + 3y = 10 =========>      2x + 3y = 10

 x + y = 7  --> by -3  ====>   -3x  - 3y  = -21
                                                  -----------------

Add the two equations and see what happens to the y-term.

@ImpracticalJoker

Note: You could also multiply by 3 and then subtract the second equation from the first.

Both options are listed. That is what makes this a lousy question.