解:
因為$2a + 7b + 3$的立方根是$3,$所以$2a + 7b + 3 = 3^{3}=27,$即$2a + 7b = 24;$
因為$3a + b - 1$的算術平方根是$4,$所以$3a + b - 1 = 4^{2}=16,$即$3a + b = 17。$
聯(lián)立方程組$\begin{cases}2a + 7b = 24\\3a + b = 17\end{cases},$
由$3a + b = 17$可得$b = 17 - 3a,$
將$b = 17 - 3a$代入$2a + 7b = 24$得:
$\begin{aligned}2a + 7(17 - 3a)&=24\\2a + 119 - 21a&=24\\-19a&=24 - 119\\-19a&=-95\\a&=5\end{aligned}$
把$a = 5$代入$b = 17 - 3a$得$b = 17 - 3×5 = 17 - 15 = 2。$
因為$9\lt14\lt16,$所以$3\lt\sqrt{14}\lt4,$$\sqrt{14}$的整數(shù)部分$c = 3。$
則$3a - b + c = 3×5 - 2 + 3 = 15 - 2 + 3 = 16,$$3a - b + c$的平方根是$\pm4。$