help me please!!!!!!!!!!!!!!!

[rachealjohnson]

how do you do this one 2x+4y=10
2x+3y=18

 

[Unco]

2x + 4y = 10 [1]
2x + 3y = 18 [2]

There is a 2x in both equations so if we subtract [2] (the second equation) from [1] (the first equation):

\(\displaystyle \mbox{ 2x + 4y = 10} \mbox{ }\) [1]
\(\displaystyle \mbox{- 2x + 3y = 18} \mbox{ }\) [2]
\(\displaystyle \mbox{ }-------------\)
\(\displaystyle \mbox{ y = -8}\)

Substitute y=-8 into [1] or [2] to find x.

 

[rachealjohnson]

Thanks I have another problem 5x-4y=-3
-2x+3y=18

 

[Unco]

5x - 4y = -3 [1]
-2x + 3y = 18 [2]

If we wanted to eliminate x (we could just as well choose y) by adding the two equations (we could just as well choose to subtract), what would be multiply [1] by and [2] by?

 

[rachealjohnson]

thank unco