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Simultaneous Equations help please?
Solve this simultaneous equation.
y=x+2
y=3xsquared
Please help me and it would help alot if you showed your
working out too. I can't do it...
5 Answers
- BieberLv 61 decade agoFavorite Answer
y=x+2
y=3x^2
So all you have to do here, is substitue 3x^2 in to the first equation's 'y':
3x^2=x+2
3x^2-x-2=0
3x^2-3x+2x-2=0
3x(x-1)+2(x-1)=0
(3x+2)(x-1)-0
x=-2/3 or 1
Now sub 1 in to the first equatoin for x:
y=3
So one solution could be: (1,3)
Now let's sub -2/3 in to the first equation for x:
y=-2/3+2
y=4/3
And another solution is:
(-2/3, 4/3)
Have a nice day :)
Source(s): Grade 10 Math - pieninjaLv 51 decade ago
if y=x+2 and y=3x^2, that means that x+2=3x^2, move them all to one side and you get 3x^2-x-2=0.
This factors to (3x+2)(x-1)=0. In order for that expression to equal zero, one of the two factors must equal zero. So set 3x+2=0 and you solve that x=-2/3 also set x-1=0 and you get x=1.
So your answers are x=-2/3 and x=1
- jimLv 41 decade ago
substitute 3x^2 for y in eq # 1 to get 3x^2 = x + 2 so 3x^2 - x - 2 = 0
using then quadratic formula x = (1 +/- sqrt(1 + 24)/6 = (1 +/- 5)/6 = 1, -2/3
- 1 decade ago
y=x+2
y=3x^2
=> x+2 = 3x^2
0 = 3x^2 - x - 2
0 = (3x + 2)(x - 1)
x = -2/3 and 1, => y = 4/3 and 3
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