Simul. Equa. - One Linear, One Second Degree (1 Viewer)

[FranzFerdinand]

Missed the lesson today -_-'
Working and answers of:

2x-5y = 3
x²-2y²-3x = 2

and

3x-2y = 2
x²-xy+y² = 21

and

3x+2y = 1
xy+y²-y = 8

.. so i could do the rest of the 40 ~_~

much appreciated

 

[speedie]

have u tried finding x in terms of y (for the linear one) or vice versa, then subbing it into the second degree one?

 

[FranzFerdinand]

yeah, i can/have done that

but i can never get correct answers and i have no clue where i am stuffing up.

 

[pLuvia]

All have you to do is make x or y the subject then sub it into the second degree equation.

Your problem might be that you are skipping steps and might have forgot to carry on the minus sign or something. I'll let some one do the whole working out

 

[speedie]

2x-5y = 3
x²-2y²-3x = 2

x=(5y+3)/2

(25y+30y+9)/4 -2y^2- (15y+9)/2=2
25y^2+30y+9-4y^2-30y+18=8
21y^2+19=0
y^2=-19/21

did u get that? lol so i didnt get any further

damn its sooo hard writing this on computer....

 

[Mountain.Dew]

2x-5y = 3
x²-2y²-3x = 2

x=(5y+3)/2

(25y+30y+9)/4 -2y^2- (15y+9)/2=2
25y^2+30y+9-4y^2-30y+18=8
21y^2+19=0
y^2=-19/21

did u get that? lol so i didnt get any further

damn its sooo hard writing this on computer....

theres something wrong with this line...eventually, u get y^2 = 1, so y = +/- 1

 

[Riviet]

2x-5y = 3
x²-2y²-3x = 2

x=(5y+3)/2

(25y+30y+9)/4 -2y^2- (15y+9)/2=2
25y^2+30y+9-4y^2-30y+18=8
21y^2+19=0
y^2=-19/21

The bit in red should be 25y². For this one, I got two points: (4,1) and (-1,-1). Just be more careful when expanding and getting rid of fractions.

Edit: changed 9/2 to 4, silly little substitution mistake

 

[FranzFerdinand]

argh. this thing is pissing me off.

for the one you guys are working on..
the answers at the back of the book are (4,1), (-1,-1)