A = alpha
B = beta
Question:
Given that p is a constant and the quadratic equation x² - 4px + 15p = 0 has roots A and B, find the values of A and B and p for which
a) A : B = 3 : 5
b) A = B + 18
PS: I got the answers but i need the workings to understand on how to do questions like this.
a) A = 6, B = 10, p = 4
b) A = 3, B = -15, p = -3 OR A = 22.5, B = 4.5, p = 13.5
Hi,
Sum of roots A + B = 4p -- (1)
Product of roots AB = 15p -- (2)
In (a), we are given that A : B = 3 : 5, so A = 3/5 B.
From (1), 8/5 B = 4p, so B = 5/2 p and A = 4p - 5/2 p = 3/2 p.
From (2), (3/2 p)(5/2 p) = 15p, from which p can be solved.
Try part (b), thanks!
Cheers,
Wen Shih
Thanks a lot Wen Shih.
Btw congrats on being new mod ;P
Hi,
Thanks :)
Cheers,
Wen Shih