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?

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- Apr 23rd 2006, 02:06 PMdigideensCurve 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?

- Apr 23rd 2006, 03:38 PMThePerfectHackerQuote:

Originally Posted by**digideens**

$\displaystyle y=\frac{12}{x}$

$\displaystyle x+y=7$

Substitute,

$\displaystyle x+\frac{12}{x}=7$

Mutiply by $\displaystyle x$ to get,

$\displaystyle x^2+12=7x$

Thus,

$\displaystyle x^2-7x+12=0$

Factor,

$\displaystyle (x-3)(x-4)=0$

Set each factor equal to zero and solve,

$\displaystyle x=3,4$

Graphically it is demonstrated below - Apr 26th 2006, 09:58 AMdigideens
thanks a lot.