TickBox Quiz #5, Question 12

GRE Quant Problem Solving
1

I’m confused how the solution is C, and not D. and how Greg came to the the realization for equation B that an “negative times an negative is a positive” Below is my logic:

Base Equation:
3x^2+11x-b (b is a positive integer)

Discriminant:
B^2-4AC

variable B is a positive integer, so i will start by plugging in 1
11^2-4(3*1)
121-12=109
(solution is +, so there’s 2 solutions)

Lets say variable B is 100.
11^2-4(3*100)
121-1200= -1279
(solution is -, so there’s 0 solutions)

Therefore the answer is D, since its dependent on the value of B

Am I missing something here?
thanks

Screenshot (15)
Screenshot (15)1920×1080 111 KB

1 Like
2

Look carefully at the discriminant equation. C = -b.

3

I came to the same conclusion. i’m guessing there must have been an error but the answer seems to be D because if B is a positive integer, then the discriminant can be either positive, 0 or negative

4

The answer is not D. Write down the discriminant.

5

It’s tricky because it says b is a “positive” integer but the equation has a negative/minus sign in front of the b.

6

the wording is very unclear because then its not truly positive…by that logic, the “-3” in the first equation would also be “positive”