Overview: 5 questions will be solved this time.Among them
           ☆2 inequalities
           ☆3 equations

[ 1/5Inequality]
    Assignment:Find the solution set of inequality e^a+e^(-a) ≥-2 .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 1 inequality：
         e ^ a + e ^ ( -a ) ≥ -2         (1)

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    From inequality(1)：
         a ∈ R (R is all real numbers),that is, in the real number range, the inequality is always established!

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    The final solution set is :
         a ∈ R (R is all real numbers),that is, in the real number range, the inequality is always established!
[ 2/5 Equation]
    Work: Find the solution of equation e^a+e^(-a) = 0 .
    Question type: Equation
    Solution:    This equation has no real solution!
[ 3/5 Equation]
    Work: Find the solution of equation e^a+e^(-a) = (√5-1)÷2 .
    Question type: Equation
    Solution:    This equation has no real solution!
[ 4/5Inequality]
    Assignment:Find the solution set of inequality cos(a) ≥-1 .
    Question type: Inequality
    Solution:
    The inequality can be reduced to 1 inequality：
         cos ( a ) ≥ -1         (1)

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    From inequality(1)：
         a ≤ -3926991/250000 或  -3926991/250000 ≤ a ≤ -4712389/500000 或  -4712389/500000 ≤ a ≤ -4712389/500000 或  -4712389/500000 ≤ a ≤ -3141593/1000000 或  -3141593/1000000 ≤ a ≤ -3141593/1000000 或  -3141593/1000000 ≤ a ≤ 3141593/1000000 或  3141593/1000000 ≤ a ≤ 3141593/1000000 或  3141593/1000000 ≤ a ≤ 4712389/500000 或  4712389/500000 ≤ a ≤ 4712389/500000 或  4712389/500000 ≤ a ≤ 15707963/1000000 或  a ≥ 15707963/1000000

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    The final solution set is :
         a ≤ -3926991/250000 或  -3926991/250000 ≤ a ≤ -4712389/500000 或  -4712389/500000 ≤ a ≤ -4712389/500000 或  -4712389/500000 ≤ a ≤ -3141593/1000000 或  -3141593/1000000 ≤ a ≤ -3141593/1000000 或  -3141593/1000000 ≤ a ≤ 3141593/1000000 或  3141593/1000000 ≤ a ≤ 3141593/1000000 或  3141593/1000000 ≤ a ≤ 4712389/500000 或  4712389/500000 ≤ a ≤ 4712389/500000 或  4712389/500000 ≤ a ≤ 15707963/1000000 或  a ≥ 15707963/1000000
    *Note: Radian.
[ 5/5 Equation]
    Work: Find the solution of equation 2cos(a) = e+1÷e .
    Question type: Equation
    Solution:    This equation has no real solution!

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