# Thread: Quadratics

1. ## Quadratics

In the xy-plane, the graph of y =2x2 −15x intersects the graph of y=x atthe points (0, 0) and (a, a) . What is the value of ‘a’ ? D

Do I factor out first?

Thanks

2. ## Re: Quadratics

$2x^2 - 15x = x$

solve for x

3. ## Re: Quadratics

Originally Posted by allo95
In the xy-plane, the graph of y =2x2 −15x intersects the graph of y=x atthe points (0, 0) and (a, a) . What is the value of ‘a’ ? D

Do I factor out first?

Thanks
Actually I'd write it slightly different: We know that (x, y) = (a, a) for some value of a. So $y = 2x^2 - 15x$ becomes $a = 2a^2 - 15a$

-Dan

4. ## Re: Quadratics

Thanks for replies. However, still not sure how to solve it.

5. ## Re: Quadratics

$2a^2 - 15a = a$

$2a^2 - 16a = 0$

$2a(a-8) = 0$

so, what is the non-zero value of $a$?

8! Thanks!!!