The equation says : what is on the left ( ) is equal to what is on the right ()

Consider a cube that has sides of length l. now consider putting the largest sphere you can inside this cube without any point on the sphere lying outside of the cube. the volume ratio -volume of the sphere/ volume of the cube is 1. 5.2 × 10−1 2. 3.8 × 10−1 3. 1.9 4. 2.5 × 10−1 5. 3.8

Answer! if you don’t mind, can you explain

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83