# Thread: Find the coordinates of these points..

1. ## Find the coordinates of these points..

two different points on the line y=2 are each exactly 13 units from the point (7,14). Draw the picture of this situation, and then find the coordinates of these points.

^so i tried setting up a cartesian coordinate plane and set the points out but i didnt know what else to do. experts?

2. Originally Posted by gabriel
two different points on the line y=2 are each exactly 13 units from the point (7,14). Draw the picture of this situation, and then find the coordinates of these points.

^so i tried setting up a cartesian coordinate plane and set the points out but i didnt know what else to do. experts?
Solve $\displaystyle \sqrt{(x-7)^2+(12)^2}=13$ for $\displaystyle x$.
You should find two values.

3. i got stuck on sqrt -13x + 158 = 13
^ and would x be an (i) integer?

4. Originally Posted by gabriel
i got stuck on sqrt -13x + 158 = 13
The part is red is comply wrong.
You need to learn to do basic algebraic operations.

5. ^how is this wrong?

ok so the problem is sqrt of (x-7)^2 + 12^2=13
so to solve this is did the following:
foiled (x-7)^2 = x^2+14x+14
while doing that, the problem would be sqrt of x^2-14x+14 (+) 144 = 13
and so on what is wrong with that?

6. Originally Posted by gabriel
ok so the problem is sqrt of (x-7)^2 + 12^2=13
so to solve this is did the following:
foiled (x-7)^2 = x^2+14x+14
while doing that, the problem would be sqrt of x^2-14x+14 (+) 144 = 13
and so on what is wrong with that?
FOIL, in my view, is a useless idea.
$\displaystyle (x-7)^2=(x-7)(x-7)=x^2-7x-7x+49=x^2-14x+49$

If you cannot do these simple operations, then you are going to have a most difficult time doing pre-calculus.

7. Originally Posted by gabriel
^how is this wrong?

ok so the problem is

$\displaystyle \sqrt{(x-7)^2 + 12^2}=13$

so to solve this is did the following:

foiled (x-7)^2 = x^2+14x+14 .....this is incorrect, you should be multiplying the -7's..not adding 7+7

while doing that, the problem would be sqrt of x^2-14x+14 (+) 144 = 13
and so on what is wrong with that?

$\displaystyle (x-7)^2=(x-7)(x-7)=x(x-7)-7(x-7)=x(x)+x(-7)-7(x)-7(-7)$

$\displaystyle =x^2-7x-7x+49=x^2-14x+49$

$\displaystyle x^2-14x+49=(13)^2$

Also $\displaystyle x^2-14x$ is not equal to $\displaystyle -13x$

$\displaystyle x-14x=-13x$

8. so what do i do when i get
sqrt of x^2-14x+49 = 13^2 or (169)

9. You do not understand this problem at all do you?