The answer is A because when you plug in the points into the distance formula, you will get square root of 17 squared plus 17 squared. Hope this helps!
If the half-life is t, then every t days, the amount of the radioactive isotope will be cut in half.
(1/2)^(number of half-lives) = 3%
number of half-lives = ln(0.03) / ln(0.5)
This gives the number of half-lives as 5.06.
Then 300 days = (5.06)(length of 1 half-life)
length of 1 half-life = 300 / 5.06 = 59.29 days
f(x) = 5x^2 - 4x
g(x) = 5x + 1
Therefore f - g = 5x^2 - 4x - (5x + 1)
= 5x^2 - 4x - 5x -1
= 5x^2 -9x - 1
Hope it helps :)