If a and b are the two solutions of the equation x2 - 5x + 4 = 0, what is the value of? Give your answer as a fraction.

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问题 If a and b are the two solutions of the equation x2 - 5x + 4 = 0, what is the value of?
Give your answer as a fraction.

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答案5/2

解析 Factoring the quadratic equation x2 - 5x + 4 = 0, you get(x - 1)(x - 4)= 0, so the two solutions are either a = 1 and fr = 4 or a = 4 and b = 1. Note that a and b are interchangeable in the expressionso the value of the expression will be the same regardless of the choices of a and b. Thus

and the correct answer is 5/2.
This explanation uses the following strategies.
Strategy 5: Simplify an Arithmetic or Algebraic Representation
Strategy 8: Search for a Mathematical Relationship
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本试题收录于: GRE QUANTITATIVE题库GRE分类
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