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xcise_science
- Master | Next Rank: 500 Posts
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Question 1.
We have the length of wire used to form a circle is circumference of the circle which means 2*pi*r, so the remains of wire used to form a square is (40 - 2*pi*r).
The area of the circle is pi*r^2 and the square is (40 - 2*pi*r)^2. It means that represent the total area of the circular and the square regions in terms of r is D: pi*r^2 + (40 - 2*pi*r)^2.
Question 2.
2^x - 2^(x-2) = 3(2^13)
-> 2^x - (2^x)/(2^2) = 3(2^13)
-> (2^2)*(2^x) - 2^x = (2^2)*3(2^13)
-> 4(2^x) - (2^x) = 3(2^15)
-> 3(2^x) = 3(2^15)
-> 2^x = 2^15
-> x = 15
The answer for this question is D:15.
Hope it's useful!
