Curve Intersections...

• April 23rd 2006, 03:06 PM
digideens
Curve Intersections...
A and B are the intersections of the curve y=12/x and the line y+x=7. Find the co-ordinates of A and B. What method do I use for this?
• April 23rd 2006, 04:38 PM
ThePerfectHacker
Quote:

Originally Posted by digideens
A and B are the intersections of the curve y=12/x and the line y+x=7. Find the co-ordinates of A and B. What method do I use for this?

You need to solve,
$y=\frac{12}{x}$
$x+y=7$
Substitute,
$x+\frac{12}{x}=7$
Mutiply by $x$ to get,
$x^2+12=7x$
Thus,
$x^2-7x+12=0$
Factor,
$(x-3)(x-4)=0$
Set each factor equal to zero and solve,
$x=3,4$

Graphically it is demonstrated below
• April 26th 2006, 10:58 AM
digideens
thanks a lot.