calculus 3: find y so distance between (6, -5) and (3, y) is 12

[Christian.]

Hello
I have worked on this problem for quite a while and I am told by the WeBwork homework website that my answer is incorrect. I am using the distance formula and quadratic equation to solve it. I think I am on the right track to solving it. I have added a photo of the problem and my current work to this post. Can any one please help me. Thanks.

 

[Deleted member 4993]

Hello
Can someone please help me with this problem? Thanks.

Find all y such that the distance between the points (6, -5) and (3,y) is 12.

This is not a calculus problem.

Distance between two points with coordinates (x₁,y₁) & (x₂,y₂) is:

D = [(x₂ - x₁)^2 + (y₂ - y₁)^2]^(1/2)

continue....

 

[Steven G]

Hello
Can someone please help me with this problem? I have attached the problem and my current work on it. Thanks.

View attachment 10074

View attachment 10073

Your last line is wrong. Also, after fixing your mistake you should simplify.
Also, do not demand that we answer your question when you want it. We will get to your problem when we have some free time.

 

[Dr.Peterson]

Hello
I have worked on this problem for quite a while and I am told by the WeBwork homework website that my answer is incorrect. I am using the distance formula and quadratic equation to solve it. I think I am on the right track to solving it. I have added a photo of the problem and my current work to this post. Can any one please help me. Thanks.

What answer did you enter?

Fix the one sign error, finish the calculation (simplify), and then tell us what you typed, and we will be in a better position to tell you why the program is rejecting it. But your basic approach is correct.

 

[Christian.]

I don't know where my sign error is, but I did re-work the problem, simplified, and circled my answer.

 

[Dr.Peterson]

I don't know where my sign error is, but I did re-work the problem, simplified, and circled my answer.

You can see the sign error by comparing to what you wrote before: you wrote 10, rather than -10, for -b.

The answer now looks correct. If you entered "16.62,-6.62", and if the instructions somewhere said to give results to the nearest hundredth, then it should have been accepted. If they said to give an exact answer in simplified radical form, then you would need to do that instead. I am surprised not to see any such instructions in the problem.

Was this answer accepted?

 

[Christian.]

I found the answer. The online homework system did not want the answer as 16.22, -6.62 but as((-10+sqrt(10^2-4(1)(-110)))/(2(1))), ((-10-sqrt(10^2-4(1)(-110)))/(2(1))). I also did mess up on that one sign. Thanks for helping.

 

[Dr.Peterson]

I found the answer. The online homework system did not want the answer as 16.22, -6.62 but as((-10+sqrt(10^2-4(1)(-110)))/(2(1))), ((-10-sqrt(10^2-4(1)(-110)))/(2(1))). I also did mess up on that one sign. Thanks for helping.

This tells me that they require an exact answer, but it doesn't have to be simplified. I hope they state that somewhere, and don't just leave you to figure it out by guessing.