Simultaneous equations-one linear, one quadratic!

Watch
This discussion is closed.
*girlie*
Badges: 5
Rep:
?
#1
Report Thread starter 15 years ago
#1
Solve x+y=2 and 3x^2-2c+y^2=2 simultaneously.

Well, i got up to 3y^2-12y+12-2y+4+y^2=2 so far?! Is that right? What next?
0
El Stevo
Badges: 1
Rep:
?
#2
Report 15 years ago
#2
is the -2c meant to be -2c or -2x?
0
*girlie*
Badges: 5
Rep:
?
#3
Report Thread starter 15 years ago
#3
(Original post by El Stevo)
is the -2c meant to be -2c or -2x?
sorry, -2x!
0
DaveManUK
Badges: 10
Rep:
?
#4
Report 15 years ago
#4
next collect all the terms together to get a quadratic in y. solve for y, and sub into one of the equations to get x. then you will have a pair of solutions for x and y.
0
DaveManUK
Badges: 10
Rep:
?
#5
Report 15 years ago
#5
I got y=1, y=3/2 and corres. values of x are x=1 x=1/2. hope that helps
0
manps
Badges: 0
Rep:
?
#6
Report 15 years ago
#6
Solve x+y=2 and 3x^2-2c+y^2=2 simultaneously.

[1] x + y = 2 -----> change this to y=2 - x

[2] 3x² - 2x + y² = 2

In [2] put (2-x) instead of y

[2] 3x² - 2x + (2-x)² = 2

...3x² - 2x + 4 - 4x + x² = 2
Rearrange in the form ax² + bx + c = 0
...4x² - 6x + 2 = 0
Take out a factor of 2
...2(2x² - 3x +1) = 0
...2x² - 3x +1=0
Solving this using the quadratic formula gives, x = 0.5 and x = 1
Substituting into either equation to find the corresponding y values gives,
(0.5, 1.5) and (1, 1)
0
*girlie*
Badges: 5
Rep:
?
#7
Report Thread starter 15 years ago
#7
thank you!!!
0
X
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

How are you feeling ahead of starting University?

I am excited and looking forward to starting (42)
13.77%
I am excited but have some apprehension around Covid-19 measures (45)
14.75%
I am concerned I will miss out on aspects of the uni experience due to new measures (106)
34.75%
I am concerned the Covid-19 measures at uni are not strong enough (30)
9.84%
I am nervous and feel I don't have enough information (66)
21.64%
Something else (let us know in the thread!) (16)
5.25%

Watched Threads

View All