You might want to watch the entire video.g3lo wrote:Hi,
In Lesson: Useful Contradictions where it talks about quadratic equations.
It shows X^2 - 10x - 24 = (X-4x)(x-6x)
Is this an error?
As when you expand it you get; X^2-10X+24 (not -24)
The "error" is intentional.
This video (at https://www.gmatprepnow.com/module/gmat- ... video/1104) is meant to show you how the two statements in a DS question will never contradict each other.
This fact helps us identify the error in factoring x^2 - 10x - 24 to get (x-4)(x-6)
At 2:55 in the video, we make a second attempt at factoring the expression to get the CORRECT factorization of (x - 12)(x + 2)
Cheers,
Brent