Question

lol

Answer 1

add both equations

Answer 2

you'll get 2x = 22

Answer 3

solve for that, and you'll get 11

Answer 4

I though that too, but that's not an answer. :(

Answer 5

thought*

Answer 6

what are the options?

Answer 7

-22
-12
-2

Answer 8

I have to go, I'll respond to this in a little bit. Sorry.

Answer 9

x + y = 12
x - y = 10

D = (1)(-1)-(1)(1)
Dx = (12)(-1)-(10)(1)
Dy = (1)(10)-(1)(12)

Answer 10

That's fine. Thanks though :)

Answer 11

Are you saying it's -22? It's asking for the x determinant if you're wondering. I just want to be able to solve the future ones. :)

Answer 12

@ambeeeerlw : Determinants are not used much any longer. However, you're apparently expected to know how to apply determinants to solving systems of linear equations. Have you tried looking up "determinants" on the 'Net? If you want to learn how do use determinants, either @tkhunny or I would be happy to help you ... but we do not give out just answers.

Answer 13

I actually wasn't expecting just answers, I was double checking his work so I'd know how to future problems. I'm not trying to just collect answers, I swear. I have looked it up, but I can;t a way that explains it well enough where I fully understand. :( Can you help me?

Answer 14

( or her work, I didn't see who it was)

Answer 15

"Cramer's Rule" is very interesting. It just works. It leans toward what we like to call an "Existence" result. This means it may or may not be very useful in the real world, but it demonstrates that (or under what conditions) the solution exists. Good thing to know.

Answer 16

My teacher didn't even mention it is "Cramer's Rule," so that's a nice factor to know.. I do online school, and I can't really get it touch with my teacher, reasoning behind me getting help from her.

Answer 17

@tkhunny typed this out for you earlier:

x + y = 12
x - y = 10

D = (1)(-1)-(1)(1)
Dx = (12)(-1)-(10)(1)
Dy = (1)(10)-(1)(12)

First, he found the "system determinant." He realized that

x + y = 12
x - y = 10

can be re-written as 1x+1y=12
1x-1y=10

which we need to do because we need those coefficients of x and y.

Notice how the coefficients (alone) are 1 1
1 -1

tkhunny now finds the "system determinant."