Carcass wrote:
If \(4 < a < 8\) and \(-3 < b < -1\), indicate all of the following expressions that must be true.
Indicate all that apply
A. a + b > 0
B. a - b > 0
C. b - a > 0
D. b - a < 0
E. 2b + a < 0
A: a + b > 0, If we take minimum value of a as 4.1 and maximum value of b in magnitude as -2.9, and check: 4.1 - 2.9 = 1.2. Option A is true.
B: a - b > 0, a is positive & b is negative as per the given condition so a - (-b) = a + b, which will be greater than 0. Option B is true.
C: b - a > 0, b is negative as per the given condition and a will become negative, -b - a will be lesser than 0. Option C is not true.
D: b - a < 0. As per the working of option C, option D is true.
E: 2b + a < 0, if b = -1.1 and a = 7.9 then, -2.2 + 7.9 = 5.7. Option E cannot be true.
The correct answer options are: A, B, and D.