The expression sqrt85x should be further simplified for which value of x?

happiness

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https://youtu.be/-yjkE_IIiZY (skip to 14:12)

How does she assume that because 235 ends in 5 that it is divisible by 5? Is this true for all values ending in 5?

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Subhotosh Khan

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https://youtu.be/-yjkE_IIiZY (skip to 14:12)

How does she assume that because 235 ends in 5 that it is divisible by 5? Is this true for all values ending in 5?

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If an integer has 5 at the unit location - then it is divisible by 5 (e.g. 15, 25, 35, 45...... etc.)
 

Dr.Peterson

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Is this true for all values ending in 5?
Yes, this is a well-known rule for divisibility. For a list of such rules, see here.

The reason for this rule is that, for example, 235 = 230 + 5; since any multiple of 10 is a multiple of 5, 230 is; and 5 is; and the sum of two multiples of 5 is also a multiple of 5.
 
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