Answer:
0.50 kg of the material would be left after 10 days.
0.25 kg of the material would be left after 20 days.
Step-by-step explanation:
We have been given that the half-life of a material is 10 days. You have one 1 kg of the material today. We are asked to find the amount of material left after 10 days and 20 days, respectively.
We will use half life formula.
, where,
A = Amount left after t units of time,
a = Initial amount,
t = Time,
h = Half-life.
Therefore, amount of the material left after 10 days would be 0.5 kg.
Therefore, amount of the material left after 20 days would be 0.25 kg.
<span>x² + y² + 14x − 4y − 28 = 0
x² +14x +y² - 4y =28
x²+2*7x +7² -7² + y² - 2*2y +2² - 2² = 28
(x+7)² + (y-2)² -7²-2² =28
</span>(x+7)² + (y-2)²=28+49+4
(x+7)² + (y-2)² =81 is the answer.