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已知
③
参考答案:③原式= \(\frac {\left ( {{a}^{\frac {1} {2}}-{a}^{-\frac {1} {2}}} \right )\left ( {a+{a}^{\frac {1} {2}}\cdot {a}^{-\frac {1} {2}}+{a}^{-1}} \right )} {{a}^{\frac {1} {2}}-{a}^{-\frac {1} {2}}}\)
= \(a + {a^{ - 1}} + 1\)
= \(7 + 1\)
= \(8\)