Question

英文数学题

The area of a circular sun spot is growing at a rate of 1,000 km2/s.
(a) How fast is the radius growing at the instant when it equals 7,000 km? (Round your answer to three decimal places.)
(b) How fast is the radius growing at the instant when the sun spot has an area of 640,000 km2? HINT [Use the area formula to determine the radius at that instant.] (Round your answer to four decimal places.)

Answer 1

一个圆形太阳黑子的面积以每秒1000km2的速度变大。
A) 半径7000km的时候它是以多快的速度而长的（约到小数点后三位）
B) 在太阳黑子的面积是640000km2 的时候半径长的多快？【用面积公式算出半径】（约到小数点后4为）

求采纳~~谢谢！

追问

我要答案。。。我也知道意思