Question

5x + 8y=-38
4x + 7y=-34
(substitution)

Answer 1

Use on of the equations to get x in respect to y

I'll use the first one:

5x + 8y = -38
5x = -8y - 38
x = (-8y - 38)/5

Substitute this in the second equation, let's see what you get

Answer 2

I'm no good at this.... :(

Answer 3

You've got to try at least. If you make a wrong, we can together make it right. Just sitting down there and letting me do all the work wouldn't be nice, would it?

Answer 4

4x+7(3x+12)=34
4x+21x+84=34
25x=34-84
25x=-50
x=-50/25
x=-2 answer.
4*-2+7y=34

Answer 5

his answer looks different from your example...why is that

Answer 6

shereenkhan , do you mind explaining what you did ? I'd very much be interested.

How did you get here --> 7(3x+12) ?

Answer 7

marucs13 , let's see what he's got for us. I have no idea, the angle he's pitching.

Answer 8

yeah...i'm so confused...

Answer 9

See, he just cowed out! Let's continue from where we were.

Answer 10

This is our derived eqn for x

x = (-8y - 38)/5

We'll subst. that value in the second eqn

4x + 7y=-34
4(-8y - 38)/5 + 7y=-34

Answer 11

Are you following?

Answer 12

yes

Answer 13

Now, we're going to multiply through by 5 to remove that fraction bit there

4(-8y - 38)/5 * 5 + 7y * 5=-34 * 5

yields:

4(-8y - 38) + 35y = -170

expanding the bracket:

-32y - 152 + 35y = -170 --> 35y - 32y = -170 + 152

3y = -18

div both sides by 3

y = -6

Answer 14

ah i get it :)

Answer 15

So, you know how to get x now?

Answer 16

oh..no

Answer 17

Remember our derived eqn for x?

x = (-8y - 38)/5

subst. y = -6 into the eqn and let's see what you got.

Answer 18

ah i thought so...i was thinking i had to substitute y=-6 in but i didn't know where... so x= (-6)/5?

Answer 19

No, where you have y in the eqn, just put -6 instead

Answer 20

x = (-8(-6) - 38)/5?

Answer 21

good! evaluate that and see what x is

Answer 22

x=(48 - 38)/5
x=(10)/5
x=2

Answer 23

You got it!

Answer 24

really?!? :D

Answer 25

So, x = 2, y = -6

Answer 26

so, those are the two answers i use?

Answer 27

Of course!

Answer 28

but...how would i show my work...there's so much here

Answer 29

Just go through every step we've worked so far, and follow them logically... good luck! :)