Answer: She combined unlike terms.
Step-by-step explanation:
You can only combine like terms. If a number has a variable, you must make sure that the number you're operating it with has the same variable raised to the same power (if applicable)
6.8w-4.7 is in its simplest form.
To be able to subtract these, 4.7 must have a ''w'' variable as follows;
6.8w-4.7w=2.1w
Answer:
x = 2 ± 2 sqrt(5)i
Step-by-step explanation:
(x – 2)^2 + 20 = 0
Subtract 20 from each side
(x – 2)^2 + 20 -20=0 -20
(x – 2)^2 =- 20
Take the square root of each side
sqrt((x – 2)^2) =±sqrt(- 20)
x-2 = ±sqrt(- 20)
We know sqrt(ab) = sqrt(a) sqrt(b)
x-2 = ±sqrt(- 1) sqrt(20)
We know the sqrt (-1) = i
x-2 = ±i sqrt(4*5)
x-2 = ±i sqrt(4) sqrt(5)
Add 2 to each side
x-2+2 = 2 ±i sqrt(4) sqrt(5)
x = 2 ±i 2 sqrt(5)
x = 2 ± 2 sqrt(5)i
(10 pounds) - (7 pounds 3 ounces) =
2.8125 pounds
The percentage of the radioactive isotope left is 25.0000%.
<h3>What is the half life?</h3>
The half life of a radioactive isotope is the time that will elapse before only half of the number of original isotopes will remain.
Now;
We are told that;
Half life (t1/2) = 55 days
Time taken (t) = 115 days
Ratio of isotope remaining = N/No
Thus;
N/No = (1/2)^t/t1/2
N/No = (1/2)^115/55
N/No = (1/2)^2
N/No =1/4
Hence, the percentage = 1/4 * 100/1 = 25.0000%
Learn more about half life of an isotope:brainly.com/question/16387602
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if Joyce saved $70
at 75% off, Joyce saved 25%
so, $70 is 25%
To find the total price which is 100%, multiply $70 by 4 ( because 25% x 4 = 100% )
so the original price is $70 x 4 = $280
