Which three of the following integers have a product that is less than
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03 Aug 2025, 10:18
Step 1: Understand the requirements
- The product of three chosen integers must be less than -85 (i.e., more negative than -85 ).
- Since the product is negative, the number of negative factors must be odd (either 1 or 3 negatives).
Step 2: Check all combinations of three integers
Let's consider possible groups of three numbers and calculate their products.
1. Checking groups with 1 negative number (two positives, one negative):
Possible two positives are from 7 and 2.
- $\((7,2,-6)=7 \times 2 \times(-6)=14 \times(-6)=-84\)$ (not less than -85 , just greater)
- $\((7,2,-5)=7 \times 2 \times(-5)=14 \times(-5)=-70\)$ (not less than -85 )
- $\((7,2,-4)=14 \times(-4)=-56(\mathrm{no})\)$
- $\((7,2,-2)=14 \times(-2)=-28(\mathrm{no})\)$
So no product less than -85 here.
2. Checking groups with 3 negatives:
Three negatives would be chosen from ( $\(\mathrm{C}, \mathrm{D}, \mathrm{E}, \mathrm{F}\)$ ): $\(-6,-5,-4,-2\)$.
Possible triplets:
- $\((-6,-5,-4)=(-6) \times(-5) \times(-4)\)$
Calculate: $\((-6 \times-5)=30,30 \times(-4)=-120\)$
Product $\(=-120\)$ (less than -85 ) --> Yes
- $\((-6,-5,-2)=(-6) \times(-5) \times(-2)\)$
$\((-6 \times-5)=30,30 \times(-2)=-60\)$
Product $\(=-60(\mathrm{no})\)$
- $\((-6,-4,-2)=(-6) \times(-4) \times(-2)\)$
$\((-6 \times-4)=24,24 \times(-2)=-48\)$
Product $\(=-48(\mathrm{no})\)$
- $\((-5,-4,-2)=(-5) \times(-4) \times(-2)\)$
$\((-5 \times-4)=20,20 \times(-2)=-40\)$
Product $\(=-40\)$ (no)
So only $\((-6,-5,-4)\)$ works here.
3. Checking groups with 1 positive and 2 negatives:
Number of negatives $=2 \rightarrow$ product is positive (since 2 negatives multiply to a positive).
We need product to be negative, so ignore these combinations.
4. Checking groups with 3 positives:
Only two positive integers: 7 and 2, so can't choose 3 positives.
5. Checking other combinations with 1 negative and 2 positives already done, none qualify
Step 3: Check combinations involving 7, and two negatives:
Try (7, -6, -5):
- $\(7 \times(-6) \times(-5)=7 \times 30=210\)$ (positive, no)
Try (7, -6, -4):
- $\(7 \times(-6) \times(-4)=7 \times 24=168\)$ (positive, no)
Try (7, -5, -4):
- $\(7 \times(-5) \times(-4)=7 \times 20=140\)$ (positive, no)
Try (2, -6, -5):
- $\(2 \times(-6) \times(-5)=2 \times 30=60\)$ (positive, no)
Step 4: Check if using $\((7,-6,-5)\)$ or $\((7,2,-6)\)$ matters:
Already done, above.
Step 5: Check groups with 1 negative and 2 positives that we might have missed:
We see no such product less than -85 .
Step 6: Check \((7, -6, -5) \) again:
Product is positive 210 , so no.
So the only combination producing product less than -85 is:
- (-6, -5, -4) from options (C), (D), and (E).
Step 7: Check if combinations $\((7,-6,-5)\)$ or $\((2,-6,-5)\)$ or $\((7,2,-6)\)$ produce product less than -85 :
No, they were positive or greater than -85 .
Step 8: Check another 3 number product example:
Try \((7, -6, 2)\):
- $\(7 \times(-6) \times 2=-84\)$ (close but not less than -85 )
Try (7, -5, 2):
- $\(7 \times(-5) \times 2=-70(\mathrm{no})\)$
Try (7, -4, 2):
- $\(7 \times(-4) \times 2=-56(\mathrm{no})\)$
Try (7, -2, 2):
- $\(7 \times(-2) \times 2=-28(\mathrm{no})\)$
Summary:
- (C) -6
- (D) -5
- (E) -4
These three integers multiplied give -120 , which is less than -85 .
No other three-number combination produces a product less than -85 .
Final answer:
The three integers with a product less than -85 are:
(C) -6 , (D) -5 , and (E) -4