Answer:
Step-by-step explanation:
As an example, iodine-131 is a radioisotope with a half-life of 8 days. It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131.
50 grams to 25 grams is one half-life. 25 grams to 12.5 grams is another half-life. So, for 50 grams to decay to 12.5 grams, two half-lives, which would take 36 days total, would need to pass. This means each half-life for element X is 18 days.
Answer:
Step-by-step explanation:
1. Swap sides
Swap sides:
2. Isolate the y
Multiply to both sides by 18:
Group like terms:
Simplify the fraction:
Multiply the fractions:
Simplify the arithmetic:
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Why learn this:
- Linear equations cannot tell you the future, but they can give you a good idea of what to expect so you can plan ahead. How long will it take you to fill your swimming pool? How much money will you earn during summer break? What are the quantities you need for your favorite recipe to make enough for all your friends?
- Linear equations explain some of the relationships between what we know and what we want to know and can help us solve a wide range of problems we might encounter in our everyday lives.
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Terms and topics
- Linear equations with one unknown
The main application of linear equations is solving problems in which an unknown variable, usually (but not always) x, is dependent on a known constant.
We solve linear equations by isolating the unknown variable on one side of the equation and simplifying the rest of the equation. When simplifying, anything that is done to one side of the equation must also be done to the other.
An equation of:
in which and are the constants and is the unknown variable, is a typical linear equation with one unknown. To solve for in this example, we would first isolate it by subtracting from both sides of the equation. We would then divide both sides of the equation by resulting in an answer of:
9514 1404 393
Answer:
4254.31
Step-by-step explanation:
The compound interest multiplier is ...
m = (1 +r/n)^(nt) . . . . annual rate r compounded n times per year, t years
For 11% compounded quarterly for 18 years, the multiplier is ...
m = (1 +0.11/4)^(4·18) = 1.0275^72 ≈ 7.0516671
If 30,000 is the future value, then the present value is ...
PV = FV/m = 30,000/7.0516671
PV ≈ 4254.31
Answer:
11) to know the 20% of 70$ we need to 70÷100×20 = 14 now the sale price will ne 70-14$ = 56$
12) same 20% of 92= 92÷100×20= 18.4 $ so now original price= 92+18.4 = 110.4
13) same 40% of 30$ = 30÷100×40 = 12$ now selling price = 30-12$= 18$
Answer:
ill take some brainliest
Step-by-step explanation: