解:(1)原式=
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-
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+2
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-3×
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=
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-2;
(2)原式=
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×
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=
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.
當(dāng)a=3,b=-2時,原式=1.
分析:(1)題涉及二次根式、負整數(shù)指數(shù)冪、特殊角的三角函數(shù)值、絕對值四個考點.在計算時,需要針對每個考點分別進行計算,然后根據(jù)實數(shù)的運算法則求得計算結(jié)果.
(2)本題的關(guān)鍵是正確進行分式的通分、約分,并準(zhǔn)確代值計算.
點評:本題考查了實數(shù)的運算及分式的化簡求值.在分式化簡過程中,首先要弄清楚運算順序,先去括號,再進行分式的乘除.