∵ b = √(a ² - 9)+ √(9 - a ²)+ 91
∴ a ² - 9 ≥ 0
9 - a ² ≥ 0
∴ a ² ≥ 9 ,a ² ≤ 9
∴ a ² = 9
a = ± 3
∵ a > 0
∴ a = 3
∴ b = √0 + √0 + 91 = 91
当 a = 3 时,则:a ³ - b = 3 ³ - 91 = 27 - 91 = - 64
∴ a ³ - b 的立方根 = ³ √(a ³ - b)= ³√(- 64)= - 4
若a,b为实数,a>0,b=根号a²-9+根号9-a²+91,求a³-b的立方根
若a,b为实数,a>0,b=根号a²-9+根号9-a²+91,求a³-b的立方根
数学人气:949 ℃时间:2019-09-30 19:21:15
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