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Show that f(x) = x3 - 15x2+75x - 50 is increasing on R. |
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Answer» Consider f(x) = x3 - 15x2+75x - 50 Domain of the function is R. f’(x) = 3x2 - 30x+75 = 3(x2 - 10+25) = 3(x - 5)(x - 5) = 3(x - 5)2 f’(x) = 0 for x = 5 for x<5 f’(x)>5 and for x>5 f’(x)>5 we can see throughout R the derivative is +ve but at x = 5 it is 0 so it is increasing. |
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