<span>The decay of 277 mg of an isotope is described by the function
A(t)= 277e-0.019t,
where t is time in years.
To find the amount left after 64 years,
We substitute t = 64 in the expression.
</span>A(t=64)= 277e-0.019(64)
or A(t=64) = 277 * e-1.216
= 277 * 0.29
= 82 mg
Number 7 I believe the answer is 74.
Equations:
m = k + 5
k = s + 2
m + k + s = 30
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Substitute for "m" and for "s"::
k+5 + k + k-2 = 30
3k +3 = 30
3k = 27
Kirsty has 9 marbles
---
Mina has 9+5 = 14 marbles
Seb has 9-2 = 7 marbles
Answer:
12m²
Step-by-step explanation:
For a rectangle, with length L and width W,
the perimeter is given as
Perimeter,
P = (2 x Length) + (2 x Width)
P = 2L + 2W
It is given that the perimeter is 48, hence
48 = 2L + 2W (divide both sides by 2)
24 = L + W
or
L = 24 - W -----> eq 1
Also realize that the Area of a Rectangle is given by
A = L x W -----> eq 2
Substituting eq 1 into eq 2,
A = (24 - W) x W
A = -W² + 24W
Recall that for a quadratic equation y = ax² + bx + c, the maxima or minima is given by y(max) = -b/2a
In this case, b = 24 and a = -1
-b/2a = -24/[ 2(-1) ] = 12
Hence for A to be maximum A(max) = 12m² (Answer)
