NCERT Exemplar - MCQs
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Last updated at July 30, 2026 by Teachoo
Ā
This question is similar to Ex 6.2, 6 - Chapter 6 Class 12 - Application of Derivatives
Transcript
Question 6 y = x (x ā 3)2 decreases for the values of x given by : 1 < x < 3 (B) x < 0 (C) x > 0 (D) 0 < x < 3/2 š(š„)=š„ć(š„ā3)ć^2 Calculating fā(š) fā(š„) = (š„ā3)^2+š„Ć2(š„ā3) fā(š„) = (š„ā3) [(š„ā3)+2š„] fā(š„) = (š„ā3) (3š„ā3) fā(š„) = (š„ā3) Ć3(š„ā1) fā(š) = š(šāš) (šāš) Putting fā(š) = 0 3(š„ā3) (š„ā1)=0 So, š = 3 , 1 Plotting points on number line Hence, f is decreasing for the š<š<š. So, the correct answer is (A)
