Find the product of all positive integer values of c such that 8x^2+15x+c=7x^2+11x has two real roots.
8x^2 + 15x + c = 7x^2 + 11x rearrange as
x^2 + 4x + c = 0
If we have two real roots the discriminant is > 0
So
4^2 - 4(1)(c) > 0
16 > 4c
4 > c
c < 4
So c = 1, 2 or 3
The product of all possible c's = 1 * 2 * 3 = 6
