# Math Help - Curve Intersections...

1. ## 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?

2. 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

3. thanks a lot.