# Homework Help

#### LiamT988

##### New member
Hi guys, i'd really appreciate if you could help with this maths problem:

A circle has equation (x-3)\^2+(y+5)\^2=25

and you have to find where y=kx intersects the circle twice

I'm assuming you use the discrimant and say that K>0 and that you substitute the y=kx into the circle equation however i keep getting the incorrect answer

Thanks

#### Jomo

##### Elite Member
It is great that you have tried to solve this. Good for you. Now can you please show us your work so we know where you need help?

#### mmm4444bot

##### Super Moderator
Staff member
… (x-3)\^2+(y+5)\^2=25 …

… keep getting the incorrect answer …
Please show your work, so that tutors can see what you're doing. Are those two back slashes typos?

Also, check out the forum's submission guidelines; you can start with this summary. Thank you!

#### LiamT988

##### New member
Hi, so what I have done is substitute y=kx into the (y-5)^2 part of the circle, so I get (k-5)^2 x then I expand the bracket to get K^2+10k+25 but I’m not sure where to go from here

#### Jomo

##### Elite Member
(k-5)^2 x
No, you did not substitute kx for y in (y-5)^2. Rather you substituted k for y in (y-5)^2 and then you multiplied by x (on the outside).

What to do next? First fix that mistake and write the whole equation...(x-3)^2+rewrite=25. Then solve this equation.

#### LiamT988

##### New member
Hi guys, i'd really appreciate if you could help with this maths problem:

A circle has equation (x-3)^2+(y+5)^2=25

and you have to find where y=kx intersects the circle twice

I'm assuming you use the discrimant and say that K>0 and that you substitute the y=kx into the circle equation however i keep getting the incorrect answer

So far what I have done is input Kx into the equation so I have (kx+5)^2 but from here I am confused

Thanks

&#x200B;

#### LiamT988

##### New member
No, you did not substitute kx for y in (y-5)^2. Rather you substituted k for y in (y-5)^2.

What to do next? First fix that mistake and write the whole equation...(x-3)^2+rewrite=25. Then solve this equation.
I have figured it out now thank you

#### Jomo

##### Elite Member
Expand, combine and then solve (x-3)^2+(kx+5)^2=25