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Zielflug [23.3K]
3 years ago
12

If the square of twice a number is 81, what is the number? I tried doing 2x^2=81 but that did not come out to the answer 4.5,-4.

5
Mathematics
1 answer:
Vlada [557]3 years ago
4 0
If the number is n then

square of 2 times a number
square of 2n
(2n)²
that was your mistake, because (2n)²=4n², not 2n²

the result is 81
(2n)²=81
square root both sides
remember positive and negative roots
2n=+/-9
divide by 2
n=+/-4.5

n=4.5 or -4.5
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Answer:

The correct solution is "4.6".

Step-by-step explanation:

Given:

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or,

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P = 76000

As we know,

⇒ A=P(1+\frac{r}{100} )^n

On substituting the values, we get

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⇒ (1+0.062)^n=\frac{100}{76}

On taking log both sides, we get

⇒ n \ log_e(1.062)=log_e(\frac{100}{76} )

⇒                   n=\frac{ln(\frac{100}{76} )}{ln(1.062)}

By putting the values of log, we get

⇒                      =4.5622

or,

⇒                      =4.6

5 0
2 years ago
A jar contains nickels and dimes. There are 20 coins in the jar, and the total value of
weeeeeb [17]

Answer:

Step-by-step explanation:

n and d are the number of nickels and dimes, respectively.

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0.05n + 0.10(20-n) = 1.40

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3 0
2 years ago
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velikii [3]
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The difference between successive terms is 10

<u><em>Explanation:</em></u>
To know the factor by which a certain pattern is increasing/decreasing, you need to subtract its successive terms.

If the subtraction gives you 10, this means that the pattern is increasing by 10

<u>Examples:</u>
<u>10, 20, 30, 40, 50, .....</u>
20 - 10 = 10
30 - 20 = 10
40 - 30 = 10
50 - 40 = 10
The difference between each two successive terms is 10. This means that each time we add 10 to the number we have in order to get the next one.
Therefore, this pattern is increasing by 10

<u>37, 47, 57 , .....</u>
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Therefore, the pattern is increasing by 10

Hope this helps :)</span>
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3 years ago
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4 0
3 years ago
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