steve816 one year ago Please help me! Find x so that the distance between the points (6, -1) and (x, 9) is 12.

1. steve816

So far, this is what I have:$12=\sqrt{x^2-12x+138}$ Not sure what to do from here :/

2. ganeshie8

still here ?

3. steve816

Yes I'm here!

4. jim_thompson5910

$\Large d = \sqrt{\left(x_{2}-x_{1}\right)^2+\left(y_{2}-y_{1}\right)^2}$ $\Large 12 = \sqrt{\left(x-6\right)^2+\left(-1-9\right)^2}$ $\Large 12 = \sqrt{\left(x-6\right)^2+\left(-10\right)^2}$ $\Large 12 = \sqrt{x^2-12x+36+100}$ $\Large 12 = \sqrt{x^2-12x+136}$ I'm not sure how you got 138. Did you mean 136??

5. steve816

Yeah, I meant 136

6. steve816

@ganeshie8 Please! I need a step by step guide.

7. ganeshie8

square both sides, what do you get ?

8. ganeshie8

$$12 = \sqrt{x^2-12x+136}$$ square both sides and get $$144 = x^2-12x+136$$ rearranging a bit $$x^2-12x-8=0$$

9. ganeshie8

you may use quadratic formula to solve x

10. steve816

Thank you ganeshie!