NEED MATH HELP QUICK!!!!!!!! (CONICS)

A

anxju

Active member
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ok so were doing conics in precalc, and i have a test tomorrow. i wasnt here for a few days, so i need help with these problems.

find the points of intersection and sketch:

x^2 + y^2 - 18x + 24y + 200 = 0

and

4x + 3y = 0

the second problem is:

y^2 - 2x - 10y + 31 = 0

and

x - y + 2 = 0

thanks!! could you tell me how you solved it? spare the asian comments!!
 
solve for x or y in the simpler smaller equation. Then subsititue the x or y into the big fucking nasty question. 1 equation 1 variable. You can now solve.
 
here for the second one the first is the same thing

1) y^2 - 2x - 10y + 31 = 0

and

2) x - y + 2 = 0

so you change the number to make it

x=y+2

y^2-2(y+2)-10y+31=0

y^2-2y-4-10y+31=0

y^2-12y+27=o

(y^2-3y)(-9y+27)

y(y-3)-9(y-3)

(y-3)(y-9)

y=3

y=9

hopefully thats what you were looking for tell me if u need any more help!
 
dont you just move the equation into y=mx+b form and then graph it? Putting that in y=mx+b would be a bitch though
 
^ oh and btw forgot to mention

you gotta replace what you got for y (3 and 9 if i remember well) and put them in the equations

x-3+2=0 x-1=0 x=1

x-9+2=0 x-7=0 x=7

(1,3) (7,9) is your answer yo! i think

 


x=y+2

You solved this wrong...

x = y - 2

y^2-2(y-2)-10y+31=0

y^2-2y-4-10y+31 = 0

y^2-12y+27 = 0

(y-3)(y-9) = 0

y = 3 and 9

solve for x

x=y-2

x=3-2=1

x=9-2=7

so your solutions are ordered pairs:

(1,3) and (7,9)
 
ya i solved that one, but yours is actually wrong. on the answer sheet its different. and i got the right answer

you make x - y + 2 =0 into x = y -2. because you subtract 2 from both sides, not add

thanks though

 
fuck i remember doing this shit.. not well though lolya but doing it that way gets you the right answer, but it takes forever and you need to graph it out on paper. they probably want you to use substitution im guessing, im pretty sure someone else already said it. just simplify one of the equations (whichever one is easier) so that either x or y is alone on the left side and all the other shit is on the other side, then (if it was x= 4y-6 for example) you substitute the whole right side into the other equation, replacing any x with (4y-6), because theyre equal. keep going till you get y, then go back and put y into any of the equations and bam. you have x and y, and u use that to get you POI. i don't really remember how though exactly. so pretty much all of that was wrong. cheers.
 
you got it wrong too

-2 * (y-2) = -2y + 2

so its x = y-2

y^2 -2y + 4 - 10y + 31 = 0

y^2 -12y + 35 = 0

(y -5)^2 * (y-7)^2 = 0

then plug and chug

lol i post to ask for help, but im the one correcting 2 people
 
wait im not wrong... x-y+2=0 so x-y=-2 x=y-2 thats it no? cause i got the good answer anyways lol? need help for the other one? and how old are you?
 
make sure you pay attention to this shit, I know it seems worthless but I can't evem begin to tell you how many times I have had to use shit like this in my post-college life aahhahahahah jk
 
in your first response you said it was x=y + 2

yeahi would like help wiht the first one, im 16. thanks
 
wait actually im kinda lost on the second one ill try to do it on a sheet of paper and hit u back if i find it cause i always end up with no knowing what x AND y are so shit's fucked up lol
 
wow, Ju asking for Hw help, what a surprise, naw man i wouldve hepled u but it's too late by now im sure.
 
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