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標題:

quadratic formula (2q)

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發問:

1. 4x^2-√40 x+3 =2(x+1)(x-1) ans. 1.58 (repeated) 2. (3x-2)(2x+1)=(3x-2)(x+1) ans. 0,2/3

最佳解答:

1) 4x^2 - √40x + 3 = 2(x^2 - 1) 4x^2 - √40x + 3 = 2x^2 - 2 2x^2 - √40x + 5 = 0 x = √40 +- √(40 - 4(2)(5)) / 4 = √40 / 4 = 2√10 / 4 = √10 / 2 = 1.58 2) (3x - 2)(2x + 1) = (3x - 2)(x + 1) 6x^2 - 4x + 3x - 2 = 3x^2 - 2x + 3x - 2 6x^2 - x - 2 = 3x^2 + x - 2 3x^2 - 2x = 0 x(3x - 2) = 0 x = 0 or 2/3

其他解答:

2. (3x-2)(2x+1)=(3x-2)(x+1) ans. 0,2/3 when 3x-2 = 0, (3x-2) cannot be canceled by both sides, x = 2/3 when x=/= 2/3, 2x+1 = x+1 x = 0 therefore, x = 0 or 2/3