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3 years ago

)Why is 3 + (−5) equal to −2?

Mathematics

1 answer:

netineya [11]3 years ago

7 0

Because + and - make - which makes you left with 3-5 which equals to -2 because it gets negative.

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A newborn baby's weight increased by 50% in one month. If the baby weighed 8 pounds at birth, how much did it weigh one month la

fomenos

It would weigh 12 lbs because 50% of 8 is 4 and 4 + 8 = 12 lbs.

7 0

4 years ago

Read 2 more answers

element X is a radioactive isotope such that every 21 years, its mass decreases by half. Given that the initial mass of a sample

pashok25 [27]

Answer:

The percentage rate of decay per year is of 3.25%.

The function showing the mass of the sample remaining after t is $A(t) = 80(0.9675)^t$

Step-by-step explanation:

Equation for decay of substance:

The equation that models the amount of a decaying substance after t years is given by:

$A(t) = A(0)(1-r)^t$

In which A(0) is the initial amount and r is the decay rate, as a decimal.

Every 21 years, its mass decreases by half.

This means that $A(21) = 0.5A(0)$ . We use this to find r, the percentage rate of decay per year.

$A(t) = A(0)(1-r)^t$

$0.5A(0) = A(0)(1-r)^{21}$

$(1-r)^{21} = 0.5$

$\sqrt[21]{(1-r)^{21}} = \sqrt[21]{0.5}$

$1 - r = 0.5^{\frac{1}{21}}$

$1 - r = 0.9675$

$r = 1 - 0.9675 = 0.0325$

The percentage rate of decay per year is of 3.25%.

Given that the initial mass of a sample of Element X is 80 grams.

This means that $A(0) = 80$

The equation is:

$A(t) = A(0)(1-r)^t$

$A(t) = 80(1-0.0325)^t$

$A(t) = 80(0.9675)^t$

The function showing the mass of the sample remaining after t is $A(t) = 80(0.9675)^t$

8 0

3 years ago

Read 2 more answers

Grandma has 1/2 of her birthday cake left . she wants her 12 grandchildren to each get the same size piece of cake to take home

eimsori [14]

Answer: 1/24

Step-by-step explanation:

you need to use kcf ( keep the first fraction change division into multiplication and flip the other fraction)

turn 12 into 12/1 and then just divide.

1/2 x 1/12

= 1/24

6 0

4 years ago

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Share £747 in the ratio 2:7 between Tom and Ben

beks73 [17]

747 divide 2= $373.5
then 373.5 in a ratio = 3:7

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3 years ago

Solve the following system of equations for y:<br> 2x + y - 3 - 0<br> and<br> 3x + 2y - 4 = 0

il63 [147K]

Step-by-step explanation:

I think all of you under stand this question so please like the answer

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3 years ago