Question

Can someone help me solve this using elimination?

2x + 3y = 4
4x + 6y = 9

First I would turn the first equation into
4x+6y=8

or would it be
8x + 3y = 4?

Answer 1

Do you multiply the 4 from the second equation with the entire second equation or only with the x variable?

Answer 2

4x + 6y = 8 is a correct way to use elimination on your first equation.

Answer 3

Could you explain the reasoning behind that? I kind of just guessed... @kmcllb

Answer 4

begin by working to eliminate the x first.

2x + 3y = 4
4x + 6y = 9
_____________

In order to do that we need to multiply the first equation by -2

-2(2x +3y = 4)
4x +6y =9

Answer 5

oh, so I don't have to multiply it by the 4 as long as one of the variables has the same value in both equations?

Answer 6

Well, in elimination you are trying to either "cross" out your X value or Y value, The way you guessed, you are eliminating your Y value. In order
to elimination your values need to be the same number. So all you did was multiply that by x2 to get your new equation; now just eliminate!

Answer 7

YEah, you're trying to "eliminate" one variable to solve for the other

Answer 8

therefore when you multiply-2 tot he first equation and then simplify it, you'll be adding the two equations together and thus the x value will be eliminated.

Answer 9

@Jhannybean how come you used a negative 2 when multiplying the equation?

Answer 10

because I am trying to "eliminate" the x to solve for the y variable.

Answer 11

Because to eliminate you NEED a NEGATIVE AND POSITIVE Y or X

Answer 12

One min brb

Answer 13

so it would be
-4x - 6y = -8
4x + 6y = 9

Answer 14

Looks like there is no solution to the system of equations, unless we did something wrong. Hmm.

Answer 15

Yes, now choose which one you would like to eliminate, X or Y.

Answer 16

so then I subtract right?

Answer 17

0x = 1, the answer is simply, "No solution" and yes that's what math does... they tell you there's always a answer but over time some of them are never solvable.

Answer 18

If you subtract them both x and y will become 0, therefore no solution.

Answer 19

oh, ok

Answer 20

thank you for the help, I was also wondering if you could help guide me through a word problem?

Answer 21

I could try. Close this question and open a new one :)

Answer 22

Yes, I will guide you, but you will have to conclude the answer among yourself

Answer 23

Roast beef has 25 g o protein and 11g of calcium per serving. A serving of mashed potatoes has 2g of protein and 25g of calcium How many servings of each are needed to supply exactly 29 g of protein and 61 g of calcium?

Answer 24

Sir, you add them...
Beef Stats + Potatoes stats = 29G and 61 Calcium....

Answer 25

The answer is: 1 Serving of Roast Beef, 2 Servings of Mashed Potatoes.

Answer 26

Could you help me write that out as the equations though, that's where I don't understand it

Answer 27

25G + 11C + 2(2G + 25C) = 29G + 61C

Answer 28

oh, thank you so much, sorry for the trouble

Answer 29

It's ok, I excel in math so for me this is easy, but I understand the struggle for you. If you live in America, Happy Thanksgiving! :)