To determine which expression cannot be used to find the diver's depth after 5 minutes, we need to identify the expressions that accurately represent the diver's descent at a rate of 8 meters per minute for 5 minutes.
The depth after 5 minutes of descending at 8 m/min would be calculated as:
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−8(5): This represents the product of the rate and time, which equals −40 meters. This expression is valid.
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−8 + (−8) + (−8) + (−8) + (−8): This is the sum of 5 instances of -8, which also equals −40 meters. This expression is valid.
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−85: This does not correspond to the descent calculation. It does not relate to the rate of descent and is not factored by the time. This expression is invalid.
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−8−8−8−8−8: This is the same as adding five instances of -8, which equals −40 meters. This expression is valid.
Based on the analysis, the expression that CANNOT be used to find her depth after 5 minutes is:
−85