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How to do the problem of page 54 12 in the third grade math book?
1. Solution: If the ball slows down by x meters per second on average, then 5-4x=0 x= 1.252. Solution: If it takes x seconds for the ball to roll 5 meters, then the final speed is 5- 1.25x, and the average speed is (5+5- 1.25x. 0? 5-8x+8=0 x=4+2√2 or x=4-2√2 ∵ Stop rolling after 4 seconds ∴ X = 4-2 √ 2 √ 1.2.