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For the function f(x)=(x−1)3(x−2)2f(x) = (x-1)^3(x-2)^2

Match the LIST-I with LIST-II

LIST-ILIST-II
A.f(x)≥0f(x) \geq 0I. x∈(−∞,1)∪(1,85)∪(2,∞)x \in (-\infty,1) \cup \left(1,\frac{8}{5}\right) \cup (2,\infty)
B.f(x)<0f(x) < 0II. x≥1x \geq 1
C.f(x)f(x) is increasing ifIII. x<1x < 1
D.f(x)f(x) is decreasing ifIV. x∈(85,2)x \in \left(\frac{8}{5},2\right)

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

(x−2)2≥0(x-2)^2\ge0 always, so the sign of ff follows (x−1)3(x-1)^3: f≥0f\ge0 for x≥1x\ge1 (A-II) and f<0f<0 for x<1x<1 (B-III). Also f′(x)=(x−1)2(x−2)(5x−8)f'(x)=(x-1)^2(x-2)(5x-8), positive when (x−2)(5x−8)>0(x-2)(5x-8)>0, i.e. on (−∞,1)∪(1,85)∪(2,∞)(-\infty,1)\cup(1,\frac85)\cup(2,\infty) (C-I), and negative on (85,2)\left(\frac85,2\right) (D-IV).

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