V= x*(10-2x)(8-2x)
for greatest volume, differentiate v w.r.t x and equate to 0,
dv/dx= (10-2x)(8-2x) + x(-2)(8-2x)+ x(10-2x)(-2)=0
you get x from solving the quadratic equation. volume will be max at that x
The perimeter is composed of two straight parts and two semicircles. We can use this to break down the problem.
We can find the straight parts easily. They are given in the problem.
straight parts: 82 x 2 = 164 m
The two semicircles make a circle. We just have to find the circumference of a circle with a diameter of 66 cm to get the length of the semicircles.
semicircles: 2(π)(66/2) = 66(3.14) = 207.24 m
answer: 164+207.24 = 371.24 m
Yes Dana is correct because he is black and it’s Black Lives Matter month
Question 21
Let's complete the square
y = 3x^2 + 6x + 5
y-5 = 3x^2 + 6x
y - 5 = 3(x^2 + 2x)
y - 5 = 3(x^2 + 2x + 1 - 1)
y - 5 = 3(x^2+2x+1) - 3
y - 5 = 3(x+1)^2 - 3
y = 3(x+1)^2 - 3 + 5
y = 3(x+1)^2 + 2
Answer: Choice D
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Question 22
Through trial and error you should find that choice D is the answer
Basically you plug in each of the given answer choices and see which results in a true statement.
For instance, with choice A we have
y < -4(x+1)^2 - 3
-7 < -4(0+1)^2 - 3
-7 < -7
which is false, so we eliminate choice A
Choice D is the answer because
y < -4(x+1)^2 - 3
-9 < -4(-2+1)^2 - 3
-9 < -7
which is true since -9 is to the left of -7 on the number line.
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Question 25
Answer: Choice B
Explanation:
The quantity (x-4)^2 is always positive regardless of what you pick for x. This is because we are squaring the (x-4). Squaring a negative leads to a positive. Eg: (-4)^2 = 16
Adding on a positive to (x-4)^2 makes the result even more positive. Therefore (x-4)^2 + 1 > 0 is true for any real number x.
Visually this means all solutions of y > (x-4)^2 + 1 reside in quadrants 1 and 2, which are above the x axis.
