HELP - MATHS

[Luke]

Right, I've got a sheet on simultaneous equations, and it was all going great until this:



Anyone any ideas?

[GirlNextDoor15]

x-3y+1 = 0
Equation 1 : x = 3y-1
Equation 2 : x2 - 3xy +y2 = 11
Substitute equation 1 into equation 2.
(3y-1)2 - 3y(3y-1) +y2 = 11
9y2 - 6y +1 - 9y2 +3y + y2 = 11
y2 - 3y -10 = 0
(y-5) (y+2) = 0
y=5 or y= -2

when y=5,
x= 3(5)-1
x= 14

when y= -2,
x= 3(-2)-1
x= -7

Answer : x= -7 or 14 , y= 5 or -2

[Luke]

brilliant, helped perfectly! thank you!