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abhistud0554
- Newbie | Next Rank: 10 Posts
- Posts: 1
- Joined: Tue May 28, 2013 2:21 am
Hi,
If -4 < a < 4 and -2 < b < -1, which of the following could NOT be the value of ab ?
A) -3
B) 0
C) 4
D) 6
E) 9
[spoiler]Solution : E.[/spoiler]
[spoiler]Step 1: Extreme values for a are GT(-4) and LT(4).
Extreme values for b are GT(-2) and LT(-1).
GT - Greater Than; LT - Less than
Step 2: Thus from step 1, we can understand that a can be positive or negative while b can only be negative, so ab can be positive and negative.
Step 3: The most negative ab can be is GT(-2)*GT(4) = GT(-8)
The most positive ab can be is GT(-4)*GT(-2)= LT(8)[/spoiler]
Can someone please help me understand step 3? I don't understand how they got the most negative and positive values for a and b individually, and how multiplying 2 extreme values together work when they are not both positive like GT(-2)*GT(4) = GT(-8) or if both are negative GT(-4)*GT(-2)= LT(8)?
If -4 < a < 4 and -2 < b < -1, which of the following could NOT be the value of ab ?
A) -3
B) 0
C) 4
D) 6
E) 9
[spoiler]Solution : E.[/spoiler]
[spoiler]Step 1: Extreme values for a are GT(-4) and LT(4).
Extreme values for b are GT(-2) and LT(-1).
GT - Greater Than; LT - Less than
Step 2: Thus from step 1, we can understand that a can be positive or negative while b can only be negative, so ab can be positive and negative.
Step 3: The most negative ab can be is GT(-2)*GT(4) = GT(-8)
The most positive ab can be is GT(-4)*GT(-2)= LT(8)[/spoiler]
Can someone please help me understand step 3? I don't understand how they got the most negative and positive values for a and b individually, and how multiplying 2 extreme values together work when they are not both positive like GT(-2)*GT(4) = GT(-8) or if both are negative GT(-4)*GT(-2)= LT(8)?
