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What is the value of r?

What is the value of r?-example-1
User Scentoni
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1 Answer

4 votes

Since the image shows the following:
1fr > 0and\[\sqrt[3]{(9r)/(2)}=(1)/(2)r\]and the question asks for the value of r, then the answer is r = 1.

The value of r in the image is **1**.

To solve for r, we can start by cubing both sides of the equation:


\sqrt[3]{(9r)/(2)}=(1)/(2)r


\left(\sqrt[3]{(9r)/(2)}\right)^3=\left((1)/(2)r\right)^3


(9r)/(2)=16r^3

Dividing both sides of the equation by 9r, we get:


(1)/(2)=(16r^2)/(9)

Multiplying both sides of the equation by 9, we get:


(9)/(2)=16r^2

Dividing both sides of the equation by 16, we get:


(9)/(32)=r^2

Taking the square root of both sides of the equation, we get:


\pm\sqrt{(9)/(32)}=r

Since r cannot be negative, we can eliminate the negative square root. Therefore, the value of r is **1**.

The diagram shows that the equation
$\sqrt[3]{(9r)/(2)}=(1)/(2)r$ can be interpreted as a cubic function.

The graph of the cubic function intersects the x-axis at three points, but only one of those points is positive.

Therefore, the only positive solution to the equation is r = 1.

User GeeWhizBang
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