Intersection of curves

Quote:

Originally Posted by bobby77

The line y=2x- 3 intersects the curve y=x^2+x-15 at the points

(a)(3,3)and(4,5)
(b)(-3,-9)and(4,5)
(c)(3,3)and(-4,-11)
(d)(-3,-9)and(-4,-11).

At a point of intersection:

$<br /> 2x-3=x^2+x-15<br />$ ,

so:

$<br /> x^2-x-12=0<br />$

Now trying the candidates for $x$ , we find that , $x=-3$ satisfies
this equation as does $x=4$ , so (b) must be the answer (assuming the
$y$ 's are OK which I suppose we can).

RonL