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1: 1.25 × (- 81 / 20) × (- 8) 2: (- 9) × (- 5 / 4) × (- 0.8) × 1 / 3 3: (- 3 / 4) × (- 8 + 10 / 3-1 / 2) 4: 3 / 4 × (- 9) + 3 / 4 × (- 15)
1、 1.25 * (- 8) * (- 81 / 20) = (- 10) * (- 81 / 20) = 81 / 2
2、 (- 9) * (1 / 3) * (- 5 / 4) * (- 0.8) = (- 3) * 1 = - 3)
3、 First, we use the distribution law = 6 - (10 / 4) + (1 / 8) = 6 - [(20 / 8) - (1 / 8)] = (48 / 8) - (19 / 8) = 29 / 8
4、 Association law = (3 / 4) * [(- 9) + (- 15)] = 3 / 4 * (- 24) = - 18
If the bottom radius of the cylinder is 4cm and the side area is 64 π cm2, then the generatrix length of the cylinder is ()
A. 16cmB. 16πcmC. 8cmD. 8πcm
According to the formula of the side area of the cylinder, the generatrix length of the cylinder is 64 π 2 π × 4 = 8cm, so C
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