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Most Important Selected Qs for JEE AdvancedMathematicsApplication of Derivatives

If the curve f(x)=3 x^3+a x^2+b x where a, b are non negative integers, cuts the x -axis at 3 distinct points. Find the minimum value of (a+b) .

Correct answer

4

Step-by-step solution

aligned f(x) & =x (2 x^2+a x+b ) D & >0 a^2-8 b & >0 a^2 & >8 b .(a, b) |_ min. & =(3,1) aligned Note that b can not be zero. (think!) a+ .b |_ . =4

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