Question
For which values of x is the expression 25x - 5x² - 100
positive?Solution
ATQ,
So, 25x - 5x² - 100 > 0
Or, 5x² - 25x + 100 < 0
Or, 5x² - 20x - 5x + 100 < 0
Or, 5x(x - 4) -5(x - 4) < 0
Or, (5x - 5)(x - 4) < 0
So, x = 1 and x = 4
Hence, the expression is positive between 1 and 4.
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