hi, could someone please show me the steps involved in solving the simultaneous equation:
$\displaystyle y = x - 8$
$\displaystyle x^2 + y = 4$
and could you tell me why you choose that particular path to get the answer
thankyou, Mark
hi, could someone please show me the steps involved in solving the simultaneous equation:
$\displaystyle y = x - 8$
$\displaystyle x^2 + y = 4$
and could you tell me why you choose that particular path to get the answer
thankyou, Mark
(1)
(2)
re arrange (2)
y = 4 - x^2
putting this back into (1)
4 - x^2 = x - 8
x^2 + x - 12 = 0
(x+4)(x-3) = 0
x = -4 or 3
when x = -4 (1) y = -4 -8 = -12 (2) (-4)^2 + y = 4 16 + y = 4 = -12
when x = 3 (1) y = 3 - 8 = -5 (2) (3)^2 + y = 4 9 + y + 4 = -5
therefore 2 answers fulfil this sim equation
x = -4 y = -12
x = 3 y = -5
I did it this way as when I saw a x squared I automatically knew it could have a negative value as well as a positive.