SOLUTION: I have been sitting here for hours trying to figure the following problems. I am working on Non-Linear Systems and have to solve the following systems. No matter how I work it I

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Question 252412: I have been sitting here for hours trying to figure the following problems. I am working on Non-Linear Systems and have to solve the following systems. No matter how I work it I can't seem to come to a solution.
1) {7x-8y=24
{xy^2=1
2) {(x+1)^2 - (y-1)^2 = 20
{x^2 - (y+2)^2 - 24
Thank you - Lori

Found 2 solutions by jim_thompson5910, Edwin McCravy:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Even though these are non-linear equations, we can still use substitution to solve them. I'll do the first one to get you started. If that doesn't help either repost or ask me.


# 1

Start with the second equation.


Divide both sides by {{y^2}}} to isolate 'x'.


Move onto the first equation.


Plug in


Multiply EVERY term by the LCD to clear out the fractions.


Get every term to the left side.


Multiply every term by -1.


Now use the rational root theorem to find that is a root to the polynomial equation above. In other words, if you plug in into , you will get 0. Because of this fact, this means that is a factor of


Now use polynomial long division to find that . So


This tells us that . Since we know that gives a root of , we can ignore this equation. So the next step is to solve for 'y'. Use the quadratic equation to find the next two solutions of or


So the three solutions in terms of 'y' are , or


From here, plug each solution (in terms of 'y') into to find the corresponding solution in terms of 'x'.


I skipped a bit of steps (since they're a bit long and I'm out of time for now), so feel free to ask about any step.

Answer by Edwin McCravy(20055)   (Show Source): You can put this solution on YOUR website!


1) 


 
solve the first equation for y:





Substitute in the second equation:





Multiply both sides by 64



Square the binomial:





Possible rational zeros of that are
± fractions whose numerators are
factors of 64 and whose denominators 
are factors of 49.

The factors of 64 are 1,2,4,8,16,32,64

The factors of 49 are 1,7,49

We try the easiest one first in hopes
the person who made up this problem
was kind.

We try x=1, so we divide by x-1

1 | 49 -336  576 -64 
  |      49 -287 289 
  ------------------
    49 -287  289 225

Doesn't leave a 0 remainder.

We try x=2, so we divide by x-2

2 | 49 -336  576 -64 
  |      98 -476 200 
  ------------------
    49 -238  100 136

Doesn't leave a 0 remainder.

We try x=4, so we divide by x-4

4 | 49 -336  576 -64 
  |     196 -560  64 
  ------------------
    49 -140   16   0

Hooray! It leaves a 0 remainder!
So we have factored the left side of
the equation 



as



So we use the zero factor property

 which gives the value 



That does not factor, so we have to use the quadratic
formula:

 











Now we must substitute each of the 3 values for x
into



Substituting 











Therefore on soluton is (4,)

-----

Substituting 





Divide through by 2



Divide both sides by 4



So another solution is 

(x,y) = (,)

---
Substituting 





Divide through by 2



Divide both sides by 4



So another solution is 

(x,y) = (,)

---

2)  {(x+1)^2 - (y-1)^2 = 20
    {x^2 - (y+2)^2 - 24

Sorry, but you left out the equal sign in the second
Re-post it corrected and we can help you.  There must be
an equal sign somewhere in that.  You probably meant for 
one of the - signs to be an = sign but we can't tell 
which one.

Edwin


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