help me i dont get this?

Question

If AD = 2x + y, BC = 7y - 2x, and x = 3, find AD

plz explain....is it like this
2x + y
2(3) + y
6 + y
if it is like this^ what is 6+y equal to?

Answer 1

You would do like you did, and get 6+y except you would make it equal to zero (6+y=0) and then subtract 6 from each side so y = -6

Here's what you do if you want to check your answer:
You want to plug -6 back into everywhere you see a y in the AD equation (2x+y) So now you have 2x-6. Then you want to solve for x. 2x-6=0 Add six to both sides to get rid of the -6 on the left. 2x=6 Then divide both sides by two to get rid of the multiplication on the left side. x=3. So you know it's right because that's what the original equation told you!

Hope I helped! :]

Answer 2

AD = 8

This problem is a little hard to answer as you state it. However, I believe you are looking at a rectangle (or a square which is, of course, also a rectangle) labeled in the common fashion of starting at one corner and labeling A-B-C-D as one goes around. If so, AD and BC are opposing sides of the rectangle/square and therefore are equal in length so the values given for their lengths are also equal.

If so, then 2x + y = 7y - 2x. Rearranging to get the y's by themselves and then to end up with only "y =" (remember, we already know x = 3), we add 2x to each side, subtract y from each side and divide by 6:

2x + y + 2x = 7y - 2x + 2x
4x + y - y = 7y - y
4x / 6 = 6y / 6
(2/3)x = y
(2/3) * 3 = y
y = 2

So, if x = 3 and y = 2, and AD = 2x + y, then AD = 2*3 + 2 = 8.

So, looking at the secondary question you asked, yes, you did it right, AD does equal 6 + y. And the trick to finding what 6 + y equals is in the information not included in the statement of the problem. If there really is nothing else, then it is NOT possible to find 6 + y as equalling some particular value rather than as a line on a graph.

Answer 3

Let's set AD = Q, and BC = W

It will make things look a little simpler, and it's more clear what you are dealing with.

Q = 2x
W = 7y - 2x

Where x = 3

You have 4 unknowns and only 2 equations. There's no way you will ever solve for 'AD'...which we called Q.

And yes, you are thinking along the correct lines.

The best you can hope for is the following:

Q = 2*3
==> Q = AD = 6

You don' even need 'BC'. I think there's some information missing, maybe even whole equations missing from this problem. But anyway, this is all you can do with this.

Hope this helps you.

Answer 4

You need one more restriction, or you can represent AD as a function of BC.
AD
= 6 + y
= 6+ (BC+6)/7
= BC + 6 6/7

Answer 5

I'm assuming BC is some unknown number you will include in your answer.

So if x=3, then BC=7y-6
solve for y
BC+6=7y
y=(BC+6)/7

now AD=2(3)+(BC+6)/7

AD= (BC+48)/7

does this look like what you are looking for?

Answer 6

AD = 2x+y = 6+y
BC = 7y -2x = 7y-6
AD +BC = 8y
AD = 8y -BC

Answer 7

It doesn't matter what "6 + y" equals because you answered the question "find AD".

Answer 8

I recommend asking your teacher before class starts.

Answer 9

iT IS IMPOSSIBLE TO SOLVE.