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JEE Main 202624 JanuaryMorning Shift
Exam
JEE Main
Year
2026
Date
24 January
Shift
Morning Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2026 · 24 January · Morning Shift · Mathematics · Functions

If the domain of the function f(x)= _ (10 x^ 2 -17 x+7) (18 x^ 2...

If the domain of the function f(x)=log⁡(10x2−17x+7)f(x)=\log _{\left(10 x^{2}-17 x+7\right)}(18x2−11x+1)\left(18 x^{2}-11 x+1\right) is (−∞,a)∪(b,c)∪(d,∞)−{e}(-\infty, a) \cup(b, c) \cup(d, \infty)-\{e\}, then 90(a+b+c+d+e)90(a+b+c+d+e) equals:

Options

  1. A170
  2. B307
  3. C316
  4. D177

Correct answer

C. 316

Step-by-step solution

For f(x)=log⁡(10x2−17x+7)(18x2−11x+1)f(x) = \log_{(10x^2-17x+7)}(18x^2-11x+1), we need:
Base >0> 0: 10x2−17x+7>0⇒10(x−1)(x−7/10)>0⇒x<7/1010x^2-17x+7 > 0 \Rightarrow 10(x-1)(x-7/10) > 0 \Rightarrow x < 7/10 or x>1x > 1
Base ≠1\neq 1: 10x2−17x+6=0⇒x=1/210x^2-17x+6 = 0 \Rightarrow x = 1/2 or x=6/5x = 6/5
Argument >0> 0: 18x2−11x+1>0⇒18(x−1/2)(x−1/9)>0⇒x<1/918x^2-11x+1 > 0 \Rightarrow 18(x-1/2)(x-1/9) > 0 \Rightarrow x < 1/9 or x>1/2x > 1/2
Intersecting conditions 1 and 3: (−∞,1/9)∪(1/2,7/10)∪(1,∞)(-\infty, 1/9) \cup (1/2, 7/10) \cup (1, \infty)
Removing base =1= 1 points: x=1/2x = 1/2 is already excluded; x=6/5∈(1,∞)x = 6/5 \in (1,\infty) must be removed.
Domain: (−∞,1/9)∪(1/2,7/10)∪(1,∞)−{6/5}(-\infty, 1/9) \cup (1/2, 7/10) \cup (1, \infty) - \{6/5\}
So a=1/9,  b=1/2,  c=7/10,  d=1,  e=6/5a = 1/9,\; b = 1/2,\; c = 7/10,\; d = 1,\; e = 6/5.
90(a+b+c+d+e)=90(19+12+710+1+65)=10+45+63+90+108=31690(a+b+c+d+e) = 90\left(\frac{1}{9}+\frac{1}{2}+\frac{7}{10}+1+\frac{6}{5}\right) = 10+45+63+90+108 = 316
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