The discriminante :
b^2-4ac
1^2 - 4 * -2 * -28 = 1 - 224 = -223
When the discriminant (b^2-4ac) is less than 0, the equation had no real solutions.
-223<0, so, 2x^2+x-28 = 0 has no real solutions.
Hope that helps :)
A equals -1/2 is the right answer
The first, third, and sixth are correct.
Any number that is divisible by 6 is already divisible by 2, but is not necessarily divisible by 12.
Counterexamples include: 6, 18, 30, 42, 54, and so on. You can find more by multiplying 6 by any odd number. However, multiplying 6 by an even number provides another "2" that would make it divisible by 12.
